21064415 has 4 divisors (see below), whose sum is σ = 25277304. Its totient is φ = 16851528.

The previous prime is 21064363. The next prime is 21064471. The reversal of 21064415 is 51446012.

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

It is a cyclic number.

It is not a de Polignac number, because 21064415 - 2²⁰ = 20015839 is a prime.

It is a Duffinian number.

It is a congruent number.

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, 2106437 + ... + 2106446.

It is an arithmetic number, because the mean of its divisors is an integer number (6319326).

Almost surely, 2^21064415 is an apocalyptic number.

21064415 is a deficient number, since it is larger than the sum of its proper divisors (4212889).

21064415 is an equidigital number, since it uses as much as digits as its factorization.

21064415 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4212888.

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 21064415 is about 4589.5985663236. The cubic root of 21064415 is about 276.1742187527.

The spelling of 21064415 in words is "twenty-one million, sixty-four thousand, four hundred fifteen".