21670564 has 12 divisors (see below), whose sum is σ = 39919600. Its totient is φ = 10264968.

The previous prime is 21670559. The next prime is 21670601. The reversal of 21670564 is 46507612.

21670564 = T₃₁₇ + T₃₁₈ + ... + T₅₄₄.

It is a happy number.

It is a super-2 number, since 2×21670564² = 939226688156192, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 142494 + ... + 142645.

Almost surely, 2^21670564 is an apocalyptic number.

It is an amenable number.

21670564 is a deficient number, since it is larger than the sum of its proper divisors (18249036).

21670564 is a wasteful number, since it uses less digits than its factorization.

21670564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285162 (or 285160 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 21670564 is about 4655.1653031874. The cubic root of 21670564 is about 278.7982680329.

The spelling of 21670564 in words is "twenty-one million, six hundred seventy thousand, five hundred sixty-four".