21878512 has 20 divisors (see below), whose sum is σ = 42654760. Its totient is φ = 10870848.

The previous prime is 21878491. The next prime is 21878531. The reversal of 21878512 is 21587812.

It is a congruent number.

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, 1587 + ... + 6802.

It is an arithmetic number, because the mean of its divisors is an integer number (2132738).

Almost surely, 2^21878512 is an apocalyptic number.

It is an amenable number.

21878512 is a deficient number, since it is larger than the sum of its proper divisors (20776248).

21878512 is a wasteful number, since it uses less digits than its factorization.

21878512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8560 (or 8554 counting only the distinct ones).

The product of its digits is 8960, while the sum is 34.

The square root of 21878512 is about 4677.4471669918. The cubic root of 21878512 is about 279.6872017121.

The spelling of 21878512 in words is "twenty-one million, eight hundred seventy-eight thousand, five hundred twelve".