21564213 has 8 divisors (see below), whose sum is σ = 31366176. Its totient is φ = 13069200.

The previous prime is 21564203. The next prime is 21564217. The reversal of 21564213 is 31246512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21564213 - 2⁵ = 21564181 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21564217) 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 7 ways as a sum of consecutive naturals, for example, 326698 + ... + 326763.

It is an arithmetic number, because the mean of its divisors is an integer number (3920772).

Almost surely, 2^21564213 is an apocalyptic number.

It is an amenable number.

21564213 is a deficient number, since it is larger than the sum of its proper divisors (9801963).

21564213 is a wasteful number, since it uses less digits than its factorization.

21564213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 653475.

The product of its digits is 1440, while the sum is 24.

The square root of 21564213 is about 4643.7283512281. The cubic root of 21564213 is about 278.3414407940.

The spelling of 21564213 in words is "twenty-one million, five hundred sixty-four thousand, two hundred thirteen".