21668808 has 32 divisors (see below), whose sum is σ = 61911360. Its totient is φ = 6191040.

The previous prime is 21668807. The next prime is 21668827. The reversal of 21668808 is 80886612.

It is not an unprimeable number, because it can be changed into a prime (21668807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64323 + ... + 64658.

It is an arithmetic number, because the mean of its divisors is an integer number (1934730).

Almost surely, 2^21668808 is an apocalyptic number.

21668808 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21668808 is an abundant number, since it is smaller than the sum of its proper divisors (40242552).

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

21668808 is a wasteful number, since it uses less digits than its factorization.

21668808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128997 (or 128993 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 39.

The square root of 21668808 is about 4654.9766916710. The cubic root of 21668808 is about 278.7907373416.

The spelling of 21668808 in words is "twenty-one million, six hundred sixty-eight thousand, eight hundred eight".