21164479 has 4 divisors (see below), whose sum is σ = 24187984. Its totient is φ = 18140976.

The previous prime is 21164477. The next prime is 21164489. The reversal of 21164479 is 97446112.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21164479 - 2¹ = 21164477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21164477) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1511742 + ... + 1511755.

It is an arithmetic number, because the mean of its divisors is an integer number (6046996).

Almost surely, 2^21164479 is an apocalyptic number.

21164479 is a deficient number, since it is larger than the sum of its proper divisors (3023505).

21164479 is an equidigital number, since it uses as much as digits as its factorization.

21164479 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3023504.

The product of its digits is 12096, while the sum is 34.

The square root of 21164479 is about 4600.4868220657. The cubic root of 21164479 is about 276.6108390444.

The spelling of 21164479 in words is "twenty-one million, one hundred sixty-four thousand, four hundred seventy-nine".