21564313 has 24 divisors (see below), whose sum is σ = 24756480. Its totient is φ = 18735360.

The previous prime is 21564311. The next prime is 21564329. The reversal of 21564313 is 31346512.

It is not a de Polignac number, because 21564313 - 2¹ = 21564311 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21564311) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 259770 + ... + 259852.

It is an arithmetic number, because the mean of its divisors is an integer number (1031520).

Almost surely, 2^21564313 is an apocalyptic number.

It is an amenable number.

21564313 is a deficient number, since it is larger than the sum of its proper divisors (3192167).

21564313 is a wasteful number, since it uses less digits than its factorization.

21564313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177 (or 160 counting only the distinct ones).

The product of its digits is 2160, while the sum is 25.

The square root of 21564313 is about 4643.7391184260. The cubic root of 21564313 is about 278.3418710454.

It can be divided in two parts, 2156 and 4313, that multiplied together give a triangular number (9298828 = T₄₃₁₂).

The spelling of 21564313 in words is "twenty-one million, five hundred sixty-four thousand, three hundred thirteen".