In order to find the extrema, we need to solve the equation
$$\frac{d}{d x} f{\left(x \right)} = 0$$
(the derivative equals zero),
and the roots of this equation are the extrema of this function:
$$\frac{d}{d x} f{\left(x \right)} = $$
the first derivative$$- \frac{1}{x \left(1 + \frac{1}{\left(x + 1\right)^{2}}\right) \left(x + 1\right)^{2}} - \frac{\operatorname{atan}{\left(\frac{1}{x + 1} \right)}}{x^{2}} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = -38713.1352198688$$
$$x_{2} = 39267.1296958188$$
$$x_{3} = -28542.0208178556$$
$$x_{4} = 21467.6772177866$$
$$x_{5} = -16675.9546105237$$
$$x_{6} = -22608.9321168514$$
$$x_{7} = 26553.2056407291$$
$$x_{8} = -40408.3279385348$$
$$x_{9} = 24858.0255275956$$
$$x_{10} = 29095.9814883742$$
$$x_{11} = -12438.2814429455$$
$$x_{12} = -31084.7905464563$$
$$x_{13} = -24304.0927725963$$
$$x_{14} = 37571.9347095174$$
$$x_{15} = -18371.0728503658$$
$$x_{16} = 35029.1445167949$$
$$x_{17} = -14133.3227523296$$
$$x_{18} = 33333.95283087$$
$$x_{19} = -37017.9440179187$$
$$x_{20} = 20620.0932430984$$
$$x_{21} = 41809.9241128867$$
$$x_{22} = -29389.6098492063$$
$$x_{23} = -19218.6384701099$$
$$x_{24} = -36170.3490556878$$
$$x_{25} = 31638.7628112381$$
$$x_{26} = 36724.3376540104$$
$$x_{27} = 16382.1999774458$$
$$x_{28} = 32486.3575977213$$
$$x_{29} = 19772.510783606$$
$$x_{30} = -39560.7314023556$$
$$x_{31} = -42103.5219828449$$
$$x_{32} = 13839.4945380289$$
$$x_{33} = -21761.3548124131$$
$$x_{34} = -20066.2076333738$$
$$x_{35} = 18077.3511272943$$
$$x_{36} = 35876.7409159601$$
$$x_{37} = 12144.3768528683$$
$$x_{38} = -25999.2600926414$$
$$x_{39} = -20913.7798763394$$
$$x_{40} = -13285.796116128$$
$$x_{41} = 40962.325735632$$
$$x_{42} = -14980.8591242028$$
$$x_{43} = 12991.9334019177$$
$$x_{44} = 28248.3888644684$$
$$x_{45} = 14687.0596694238$$
$$x_{46} = -15828.403521626$$
$$x_{47} = -26846.8458325775$$
$$x_{48} = 38419.5320628141$$
$$x_{49} = 34181.5484799048$$
$$x_{50} = -33627.5671310672$$
$$x_{51} = -34475.1605739596$$
$$x_{52} = 30791.1685052914$$
$$x_{53} = -41255.9248056479$$
$$x_{54} = -23456.5115149074$$
$$x_{55} = -31932.3820648697$$
$$x_{56} = 40114.7275918786$$
$$x_{57} = -17523.5113353603$$
$$x_{58} = 24010.4368207144$$
$$x_{59} = -27694.4327789588$$
$$x_{60} = 18924.9300119884$$
$$x_{61} = 15534.6282921618$$
$$x_{62} = -11590.7816866689$$
$$x_{63} = -32779.9742781724$$
$$x_{64} = 17229.7743598899$$
$$x_{65} = 23162.8491300524$$
$$x_{66} = -37865.5394159643$$
$$x_{67} = 29943.5747172376$$
$$x_{68} = -35322.754562243$$
$$x_{69} = 22315.2625572719$$
$$x_{70} = 42657.5227105104$$
$$x_{71} = 27400.7968963701$$
$$x_{72} = 25705.6151608336$$
$$x_{73} = -30237.1997847744$$
$$x_{74} = -25151.6756894288$$
The values of the extrema at the points:
(-38713.135219868775, 6.67259136841639e-10)
(39267.129695818796, 6.48530829732567e-10)
(-28542.0208178556, 1.22756862217974e-9)
(21467.67721778657, 2.16974979767013e-9)
(-16675.954610523724, 3.59620660768918e-9)
(-22608.93211685139, 1.95640655535823e-9)
(26553.205640729146, 1.41823998921993e-9)
(-40408.32793853478, 6.12447671086199e-10)
(24858.02552759563, 1.61826361574189e-9)
(29095.981488374244, 1.18118806564866e-9)
(-12438.28144294554, 6.46419066243512e-9)
(-31084.79054645631, 1.03494692997068e-9)
(-24304.092772596345, 1.69300811864258e-9)
(37571.934709517365, 7.08371896761955e-10)
(-18371.072850365847, 2.96315658277877e-9)
(35029.144516794884, 8.14945450835003e-10)
(-14133.322752329579, 5.00659170286485e-9)
(33333.95283086999, 8.99939550110859e-10)
(-37017.94401791872, 7.29771911217127e-10)
(20620.093243098447, 2.35178539413593e-9)
(41809.92411288666, 5.72045869531599e-10)
(-29389.609849206256, 1.15778291257051e-9)
(-19218.63847010987, 2.70755547384604e-9)
(-36170.349055687824, 7.64375233845422e-10)
(31638.762811238146, 9.98958135292254e-10)
(36724.33765401041, 7.41447202181794e-10)
(16382.199977445838, 3.72588154948822e-9)
(32486.357597721264, 9.47511719740814e-10)
(19772.510783606034, 2.55772821004387e-9)
(-39560.7314023556, 6.38972773591382e-10)
(-42103.52198284493, 5.64122552501214e-10)
(13839.494538028881, 5.22069308231418e-9)
(-21761.354812413127, 2.11177720253702e-9)
(-20066.20763337377, 2.483653690973e-9)
(18077.35112729431, 3.05989404664113e-9)
(35876.740915960145, 7.76894284035597e-10)
(12144.37685286826, 6.77975138967274e-9)
(-25999.26009264145, 1.47943104169953e-9)
(-20913.77987633935, 2.28641837051175e-9)
(-13285.796116128002, 5.66575149557727e-9)
(40962.32573563201, 5.95964216503072e-10)
(-14980.859124202765, 4.45610638036359e-9)
(12991.933401917673, 5.92405389728132e-9)
(28248.38886446838, 1.25313326838351e-9)
(14687.059669423787, 4.63554404460099e-9)
(-15828.40352162596, 3.99165695838519e-9)
(-26846.845832577495, 1.38748928865775e-9)
(38419.532062814134, 6.77461398101581e-10)
(34181.54847990477, 8.5586216575936e-10)
(-33627.567131067175, 8.84345597638102e-10)
(-34475.16057395957, 8.41395145654967e-10)
(30791.168505291433, 1.05471119250392e-9)
(-41255.92480564787, 5.87540587517085e-10)
(-23456.51151490741, 1.81757218374837e-9)
(-31932.382064869704, 9.80733401811401e-10)
(40114.727591878574, 6.21414637624172e-10)
(-17523.511335360265, 3.25673570906596e-9)
(24010.43682071438, 1.73452989711967e-9)
(-27694.43277895881, 1.30385931050996e-9)
(18924.93001198843, 2.7919554733028e-9)
(15534.628292161771, 4.14352832164945e-9)
(-11590.781686668874, 7.44409689841905e-9)
(-32779.97427817244, 9.30670679771221e-10)
(17229.7743598899, 3.36833760748769e-9)
(23162.84913005241, 1.86379135795193e-9)
(-37865.539415964275, 6.97466211937086e-10)
(29943.57471723757, 1.11526533724678e-9)
(-35322.75456224295, 8.01499337596261e-10)
(22315.262557271926, 2.00805931152482e-9)
(42657.52271051041, 5.49539048893644e-10)
(27400.79689637011, 1.33185750791324e-9)
(25705.61516083358, 1.51330721384053e-9)
(-30237.19978477445, 1.09378313860317e-9)
(-25151.675689428797, 1.58082362640784e-9)
Intervals of increase and decrease of the function:Let's find intervals where the function increases and decreases, as well as minima and maxima of the function, for this let's look how the function behaves itself in the extremas and at the slightest deviation from:
The function has no minima
The function has no maxima
Increasing at the entire real axis