21870639684 has 24 divisors (see below), whose sum is σ = 56701658720. Its totient is φ = 7290213192.

The previous prime is 21870639683. The next prime is 21870639743. The reversal of 21870639684 is 48693607812.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 21870639684.

It is not an unprimeable number, because it can be changed into a prime (21870639683) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 101252854 + ... + 101253069.

Almost surely, 2^21870639684 is an apocalyptic number.

It is an amenable number.

21870639684 is an abundant number, since it is smaller than the sum of its proper divisors (34831019036).

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

21870639684 is a wasteful number, since it uses less digits than its factorization.

21870639684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202505936 (or 202505928 counting only the distinct ones).

The product of its (nonzero) digits is 3483648, while the sum is 54.

The spelling of 21870639684 in words is "twenty-one billion, eight hundred seventy million, six hundred thirty-nine thousand, six hundred eighty-four".