21123251044 has 36 divisors (see below), whose sum is σ = 43705861500. Its totient is φ = 8904409920.

The previous prime is 21123250987. The next prime is 21123251047. The reversal of 21123251044 is 44015232112.

It can be written as a sum of positive squares in 2 ways, for example, as 3556929600 + 17566321444 = 59640^2 + 132538^2 .

It is not an unprimeable number, because it can be changed into a prime (21123251047) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 871419 + ... + 895330.

Almost surely, 2^21123251044 is an apocalyptic number.

It is an amenable number.

21123251044 is an abundant number, since it is smaller than the sum of its proper divisors (22582610456).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21123251044 is a wasteful number, since it uses less digits than its factorization.

21123251044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1766828 (or 1766819 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

Adding to 21123251044 its reverse (44015232112), we get a palindrome (65138483156).

The spelling of 21123251044 in words is "twenty-one billion, one hundred twenty-three million, two hundred fifty-one thousand, forty-four".