21212021988 has 48 divisors (see below), whose sum is σ = 55203308160. Its totient is φ = 7043779872.

The previous prime is 21212021959. The next prime is 21212022019. The reversal of 21212021988 is 88912021212.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 344995 + ... + 401802.

It is an arithmetic number, because the mean of its divisors is an integer number (1150068920).

Almost surely, 2^21212021988 is an apocalyptic number.

It is an amenable number.

21212021988 is an abundant number, since it is smaller than the sum of its proper divisors (33991286172).

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

21212021988 is a wasteful number, since it uses less digits than its factorization.

21212021988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 747073 (or 747065 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 36.

The spelling of 21212021988 in words is "twenty-one billion, two hundred twelve million, twenty-one thousand, nine hundred eighty-eight".