21253125621 has 32 divisors (see below), whose sum is σ = 36712560640. Its totient is φ = 10620414144.

The previous prime is 21253125599. The next prime is 21253125631. The reversal of 21253125621 is 12652135212.

It is not a de Polignac number, because 21253125621 - 2⁷ = 21253125493 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253125631) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2043505 + ... + 2053878.

It is an arithmetic number, because the mean of its divisors is an integer number (1147267520).

Almost surely, 2^21253125621 is an apocalyptic number.

21253125621 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21253125621 is a deficient number, since it is larger than the sum of its proper divisors (15459435019).

21253125621 is a wasteful number, since it uses less digits than its factorization.

21253125621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4097425.

The product of its digits is 7200, while the sum is 30.

The spelling of 21253125621 in words is "twenty-one billion, two hundred fifty-three million, one hundred twenty-five thousand, six hundred twenty-one".