125991891 has 6 divisors (see below), whose sum is σ = 181988300. Its totient is φ = 83994588.

The previous prime is 125991889. The next prime is 125991923. The reversal of 125991891 is 198199521.

It is not a de Polignac number, because 125991891 - 2¹ = 125991889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (125991821) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6999541 + ... + 6999558.

Almost surely, 2^125991891 is an apocalyptic number.

125991891 is a deficient number, since it is larger than the sum of its proper divisors (55996409).

125991891 is a wasteful number, since it uses less digits than its factorization.

125991891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13999105 (or 13999102 counting only the distinct ones).

The product of its digits is 58320, while the sum is 45.

The square root of 125991891 is about 11224.6109509417. The cubic root of 125991891 is about 501.3190385480.

It can be divided in two parts, 125 and 991891, that added together give a square (992016 = 996²).

The spelling of 125991891 in words is "one hundred twenty-five million, nine hundred ninety-one thousand, eight hundred ninety-one".