125721804021 has 16 divisors (see below), whose sum is σ = 183410730048. Its totient is φ = 75968928000.

The previous prime is 125721804001. The next prime is 125721804031. The reversal of 125721804021 is 120408127521.

It is not a de Polignac number, because 125721804021 - 2⁹ = 125721803509 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (125721804001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5641330 + ... + 5663571.

It is an arithmetic number, because the mean of its divisors is an integer number (11463170628).

Almost surely, 2^125721804021 is an apocalyptic number.

125721804021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

125721804021 is a deficient number, since it is larger than the sum of its proper divisors (57688926027).

125721804021 is a wasteful number, since it uses less digits than its factorization.

125721804021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11305252.

The product of its (nonzero) digits is 8960, while the sum is 33.

The spelling of 125721804021 in words is "one hundred twenty-five billion, seven hundred twenty-one million, eight hundred four thousand, twenty-one".