21520531404 has 36 divisors (see below), whose sum is σ = 57599070984. Its totient is φ = 6751539072.

The previous prime is 21520531379. The next prime is 21520531411. The reversal of 21520531404 is 40413502512.

21520531404 is a `hidden beast` number, since 21 + 5 + 205 + 31 + 404 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21520531404² (a number of 21 digits) contains 22 as substring.

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, 17581522 + ... + 17582745.

It is an arithmetic number, because the mean of its divisors is an integer number (1599974194).

Almost surely, 2^21520531404 is an apocalyptic number.

It is an amenable number.

21520531404 is an abundant number, since it is smaller than the sum of its proper divisors (36078539580).

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

21520531404 is a wasteful number, since it uses less digits than its factorization.

21520531404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35164294 (or 35164289 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The spelling of 21520531404 in words is "twenty-one billion, five hundred twenty million, five hundred thirty-one thousand, four hundred four".