21131265225128 has 32 divisors (see below), whose sum is σ = 40587825456360. Its totient is φ = 10307849349120.

The previous prime is 21131265225113. The next prime is 21131265225137. The reversal of 21131265225128 is 82152256213112.

It can be written as a sum of positive squares in 4 ways, for example, as 13308940052164 + 7822325172964 = 3648142^2 + 2796842^2 .

It is a Harshad number since it is a multiple of its sum of digits (41).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 61498250 + ... + 61840902.

Almost surely, 2^{21131265225128} is an apocalyptic number.

It is an amenable number.

21131265225128 is a deficient number, since it is larger than the sum of its proper divisors (19456560231232).

21131265225128 is a wasteful number, since it uses less digits than its factorization.

21131265225128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 530717 (or 530713 counting only the distinct ones).

The product of its digits is 115200, while the sum is 41.

The spelling of 21131265225128 in words is "twenty-one trillion, one hundred thirty-one billion, two hundred sixty-five million, two hundred twenty-five thousand, one hundred twenty-eight".