21789988 has 24 divisors (see below), whose sum is σ = 44047584. Its totient is φ = 9321600.

The previous prime is 21789967. The next prime is 21789997. The reversal of 21789988 is 88998712.

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, 13818 + ... + 15313.

It is an arithmetic number, because the mean of its divisors is an integer number (1835316).

Almost surely, 2^21789988 is an apocalyptic number.

It is an amenable number.

21789988 is an abundant number, since it is smaller than the sum of its proper divisors (22257596).

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

21789988 is a wasteful number, since it uses less digits than its factorization.

21789988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29163 (or 29161 counting only the distinct ones).

The product of its digits is 580608, while the sum is 52.

The square root of 21789988 is about 4667.9747214397. The cubic root of 21789988 is about 279.3094719084.

The spelling of 21789988 in words is "twenty-one million, seven hundred eighty-nine thousand, nine hundred eighty-eight".