125665727566521 has 16 divisors (see below), whose sum is σ = 169226526472128. Its totient is φ = 82941170280000.

The previous prime is 125665727566481. The next prime is 125665727566529.

It is a happy number.

125665727566521 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 125665727566521 - 2²¹ = 125665725469369 is a prime.

It is not an unprimeable number, because it can be changed into a prime (125665727566529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12389955 + ... + 20120696.

It is an arithmetic number, because the mean of its divisors is an integer number (10576657904508).

Almost surely, 2^{125665727566521} is an apocalyptic number.

It is an amenable number.

125665727566521 is a deficient number, since it is larger than the sum of its proper divisors (43560798905607).

125665727566521 is a wasteful number, since it uses less digits than its factorization.

125665727566521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32523512.

The product of its digits is 317520000, while the sum is 66.

The spelling of 125665727566521 in words is "one hundred twenty-five trillion, six hundred sixty-five billion, seven hundred twenty-seven million, five hundred sixty-six thousand, five hundred twenty-one".