21070864 has 20 divisors (see below), whose sum is σ = 41495980. Its totient is φ = 10362240.

The previous prime is 21070859. The next prime is 21070873. The reversal of 21070864 is 46807012.

It can be written as a sum of positive squares in 2 ways, for example, as 4326400 + 16744464 = 2080^2 + 4092^2 .

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, 9819 + ... + 11770.

It is an arithmetic number, because the mean of its divisors is an integer number (2074799).

Almost surely, 2^21070864 is an apocalyptic number.

It is an amenable number.

21070864 is a deficient number, since it is larger than the sum of its proper divisors (20425116).

21070864 is a wasteful number, since it uses less digits than its factorization.

21070864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21658 (or 21652 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 21070864 is about 4590.3010794500. The cubic root of 21070864 is about 276.2024000212.

Adding to 21070864 its reverse (46807012), we get a palindrome (67877876).

The spelling of 21070864 in words is "twenty-one million, seventy thousand, eight hundred sixty-four".