21315970 has 24 divisors (see below), whose sum is σ = 41550516. Its totient is φ = 7869888.

The previous prime is 21315961. The next prime is 21315989. The reversal of 21315970 is 7951312.

It can be written as a sum of positive squares in 6 ways, for example, as 1682209 + 19633761 = 1297^2 + 4431^2 .

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4617 + ... + 7996.

Almost surely, 2^21315970 is an apocalyptic number.

21315970 is a deficient number, since it is larger than the sum of its proper divisors (20234546).

21315970 is a wasteful number, since it uses less digits than its factorization.

21315970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12646 (or 12633 counting only the distinct ones).

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21315970 is about 4616.9221349293. The cubic root of 21315970 is about 277.2692451738.

The spelling of 21315970 in words is "twenty-one million, three hundred fifteen thousand, nine hundred seventy".