21908664 has 32 divisors (see below), whose sum is σ = 60858000. Its totient is φ = 7302816.

The previous prime is 21908657. The next prime is 21908671. The reversal of 21908664 is 46680912.

It is an interprime number because it is at equal distance from previous prime (21908657) and next prime (21908671).

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

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, 50499 + ... + 50930.

Almost surely, 2^21908664 is an apocalyptic number.

21908664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21908664 is an abundant number, since it is smaller than the sum of its proper divisors (38949336).

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

21908664 is a wasteful number, since it uses less digits than its factorization.

21908664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101444 (or 101434 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 21908664 is about 4680.6691829267. The cubic root of 21908664 is about 279.8156269209.

The spelling of 21908664 in words is "twenty-one million, nine hundred eight thousand, six hundred sixty-four".