21788990 has 16 divisors (see below), whose sum is σ = 39718080. Its totient is φ = 8604960.

The previous prime is 21788983. The next prime is 21789007. The reversal of 21788990 is 9988712.

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, 13001 + ... + 14580.

It is an arithmetic number, because the mean of its divisors is an integer number (2482380).

Almost surely, 2^21788990 is an apocalyptic number.

21788990 is a deficient number, since it is larger than the sum of its proper divisors (17929090).

21788990 is a wasteful number, since it uses less digits than its factorization.

21788990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27667.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 21788990 is about 4667.8678216076. The cubic root of 21788990 is about 279.3052076395.

The spelling of 21788990 in words is "twenty-one million, seven hundred eighty-eight thousand, nine hundred ninety".