125555555521 has 24 divisors (see below), whose sum is σ = 145578270240. Its totient is φ = 107369932800.

The previous prime is 125555555507. The next prime is 125555555537.

125555555521 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 125555555521 - 2¹⁹ = 125555031233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (125555555501) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6606010 + ... + 6624988.

It is an arithmetic number, because the mean of its divisors is an integer number (6065761260).

Almost surely, 2^125555555521 is an apocalyptic number.

125555555521 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

125555555521 is a deficient number, since it is larger than the sum of its proper divisors (20022714719).

125555555521 is a wasteful number, since it uses less digits than its factorization.

125555555521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21105 (or 21088 counting only the distinct ones).

The product of its digits is 1562500, while the sum is 46.

The spelling of 125555555521 in words is "one hundred twenty-five billion, five hundred fifty-five million, five hundred fifty-five thousand, five hundred twenty-one".