21808708 has 12 divisors (see below), whose sum is σ = 38223360. Its totient is φ = 10887752.

The previous prime is 21808687. The next prime is 21808711. The reversal of 21808708 is 80780812.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 916 + ... + 6667.

It is an arithmetic number, because the mean of its divisors is an integer number (3185280).

Almost surely, 2^21808708 is an apocalyptic number.

It is an amenable number.

21808708 is a deficient number, since it is larger than the sum of its proper divisors (16414652).

21808708 is a wasteful number, since it uses less digits than its factorization.

21808708 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8306 (or 8304 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 34.

The square root of 21808708 is about 4669.9794432096. The cubic root of 21808708 is about 279.3894348818.

The spelling of 21808708 in words is "twenty-one million, eight hundred eight thousand, seven hundred eight".