21065870 has 64 divisors (see below), whose sum is σ = 46725120. Its totient is φ = 6676992.

The previous prime is 21065843. The next prime is 21065887. The reversal of 21065870 is 7856012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 62342 + ... + 62678.

It is an arithmetic number, because the mean of its divisors is an integer number (730080).

Almost surely, 2^21065870 is an apocalyptic number.

21065870 is an abundant number, since it is smaller than the sum of its proper divisors (25659250).

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

21065870 is a wasteful number, since it uses less digits than its factorization.

21065870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417.

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 21065870 is about 4589.7570741816. The cubic root of 21065870 is about 276.1805774107.

The spelling of 21065870 in words is "twenty-one million, sixty-five thousand, eight hundred seventy".