21659994 has 32 divisors (see below), whose sum is σ = 48386880. Its totient is φ = 7182000.

The previous prime is 21659993. The next prime is 21659999. The reversal of 21659994 is 49995612.

It is not an unprimeable number, because it can be changed into a prime (21659993) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10444 + ... + 12344.

It is an arithmetic number, because the mean of its divisors is an integer number (1512090).

Almost surely, 2^21659994 is an apocalyptic number.

21659994 is an abundant number, since it is smaller than the sum of its proper divisors (26726886).

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

21659994 is a wasteful number, since it uses less digits than its factorization.

21659994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2123 (or 2117 counting only the distinct ones).

The product of its digits is 174960, while the sum is 45.

The square root of 21659994 is about 4654.0298666854. The cubic root of 21659994 is about 278.7529319270.

The spelling of 21659994 in words is "twenty-one million, six hundred fifty-nine thousand, nine hundred ninety-four".