21680908 has 6 divisors (see below), whose sum is σ = 37941596. Its totient is φ = 10840452.

The previous prime is 21680887. The next prime is 21680909. The reversal of 21680908 is 80908612.

It is not an unprimeable number, because it can be changed into a prime (21680909) 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 as a sum of consecutive naturals, namely, 2710110 + ... + 2710117.

Almost surely, 2^21680908 is an apocalyptic number.

It is an amenable number.

21680908 is a deficient number, since it is larger than the sum of its proper divisors (16260688).

21680908 is a wasteful number, since it uses less digits than its factorization.

21680908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5420231 (or 5420229 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 21680908 is about 4656.2761945572. The cubic root of 21680908 is about 278.8426205249.

The spelling of 21680908 in words is "twenty-one million, six hundred eighty thousand, nine hundred eight".