21680868 has 24 divisors (see below), whose sum is σ = 55188000. Its totient is φ = 6569920.

The previous prime is 21680861. The next prime is 21680887. The reversal of 21680868 is 86808612.

It is not an unprimeable number, because it can be changed into a prime (21680861) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 81993 + ... + 82256.

It is an arithmetic number, because the mean of its divisors is an integer number (2299500).

Almost surely, 2^21680868 is an apocalyptic number.

It is an amenable number.

21680868 is an abundant number, since it is smaller than the sum of its proper divisors (33507132).

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

21680868 is a wasteful number, since it uses less digits than its factorization.

21680868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164267 (or 164265 counting only the distinct ones).

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

The square root of 21680868 is about 4656.2718992774. The cubic root of 21680868 is about 278.8424490420.

The spelling of 21680868 in words is "twenty-one million, six hundred eighty thousand, eight hundred sixty-eight".