21318970 has 24 divisors (see below), whose sum is σ = 39321396. Its totient is φ = 8322048.

The previous prime is 21318967. The next prime is 21318977. The reversal of 21318970 is 7981312.

It can be written as a sum of positive squares in 2 ways, for example, as 21169201 + 149769 = 4601^2 + 387^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is a plaindrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (21318977) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17914 + ... + 19066.

Almost surely, 2^21318970 is an apocalyptic number.

21318970 is a deficient number, since it is larger than the sum of its proper divisors (18002426).

21318970 is a wasteful number, since it uses less digits than its factorization.

21318970 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1246 (or 1203 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 21318970 is about 4617.2470152679. The cubic root of 21318970 is about 277.2822521465.

The spelling of 21318970 in words is "twenty-one million, three hundred eighteen thousand, nine hundred seventy".