21216473808 has 40 divisors (see below), whose sum is σ = 55145497248. Its totient is φ = 7028767872.

The previous prime is 21216473791. The next prime is 21216473813. The reversal of 21216473808 is 80837461212.

It is a self number, because there is not a number n which added to its sum of digits gives 21216473808.

It is a congruent number.

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, 1348035 + ... + 1363682.

Almost surely, 2^21216473808 is an apocalyptic number.

It is an amenable number.

21216473808 is an abundant number, since it is smaller than the sum of its proper divisors (33929023440).

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

21216473808 is a wasteful number, since it uses less digits than its factorization.

21216473808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2711891 (or 2711885 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 42.

The spelling of 21216473808 in words is "twenty-one billion, two hundred sixteen million, four hundred seventy-three thousand, eight hundred eight".