21204431557632 has 132 divisors (see below), whose sum is σ = 61544581202260. Its totient is φ = 7031520755712.

The previous prime is 21204431557501. The next prime is 21204431557649. The reversal of 21204431557632 is 23675513440212.

21204431557632 is a `hidden beast` number, since 2 + 1 + 2 + 0 + 4 + 4 + 3 + 1 + 5 + 5 + 7 + 632 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 2994616406016 + 18209815151616 = 1730496^2 + 4267296^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4182007 + ... + 7739382.

Almost surely, 2^{21204431557632} is an apocalyptic number.

It is an amenable number.

21204431557632 is an abundant number, since it is smaller than the sum of its proper divisors (40340149644628).

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

21204431557632 is a wasteful number, since it uses less digits than its factorization.

21204431557632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11921608 (or 11921587 counting only the distinct ones).

The product of its (nonzero) digits is 1209600, while the sum is 45.

Adding to 21204431557632 its reverse (23675513440212), we get a palindrome (44879944997844).

The spelling of 21204431557632 in words is "twenty-one trillion, two hundred four billion, four hundred thirty-one million, five hundred fifty-seven thousand, six hundred thirty-two".