125135721 has 12 divisors (see below), whose sum is σ = 181072372. Its totient is φ = 83275776.

The previous prime is 125135711. The next prime is 125135737. The reversal of 125135721 is 127531521.

It can be written as a sum of positive squares in 2 ways, for example, as 115863696 + 9272025 = 10764^2 + 3045^2 .

It is not a de Polignac number, because 125135721 - 2¹³ = 125127529 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (125135711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6856 + ... + 17241.

Almost surely, 2^125135721 is an apocalyptic number.

It is an amenable number.

125135721 is a deficient number, since it is larger than the sum of its proper divisors (55936651).

125135721 is a wasteful number, since it uses less digits than its factorization.

125135721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24680 (or 24677 counting only the distinct ones).

The product of its digits is 2100, while the sum is 27.

The square root of 125135721 is about 11186.4078684804. The cubic root of 125135721 is about 500.1808958788.

The spelling of 125135721 in words is "one hundred twenty-five million, one hundred thirty-five thousand, seven hundred twenty-one".