21452635621 has 4 divisors (see below), whose sum is σ = 21472264012. Its totient is φ = 21433007232.

The previous prime is 21452635613. The next prime is 21452635627. The reversal of 21452635621 is 12653625412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19352704996 + 2099930625 = 139114^2 + 45825^2 .

It is a cyclic number.

It is not a de Polignac number, because 21452635621 - 2³ = 21452635613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21452635627) 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 3 ways as a sum of consecutive naturals, for example, 9812556 + ... + 9814741.

It is an arithmetic number, because the mean of its divisors is an integer number (5368066003).

Almost surely, 2^21452635621 is an apocalyptic number.

It is an amenable number.

21452635621 is a deficient number, since it is larger than the sum of its proper divisors (19628391).

21452635621 is a wasteful number, since it uses less digits than its factorization.

21452635621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19628390.

The product of its digits is 86400, while the sum is 37.

The spelling of 21452635621 in words is "twenty-one billion, four hundred fifty-two million, six hundred thirty-five thousand, six hundred twenty-one".