21570645 has 16 divisors (see below), whose sum is σ = 34696512. Its totient is φ = 11443200.

The previous prime is 21570631. The next prime is 21570709. The reversal of 21570645 is 54607512.

It is not a de Polignac number, because 21570645 - 2⁵ = 21570613 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 831 + ... + 6620.

It is an arithmetic number, because the mean of its divisors is an integer number (2168532).

Almost surely, 2^21570645 is an apocalyptic number.

It is an amenable number.

21570645 is a deficient number, since it is larger than the sum of its proper divisors (13125867).

21570645 is a wasteful number, since it uses less digits than its factorization.

21570645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7652.

The product of its (nonzero) digits is 8400, while the sum is 30.

The square root of 21570645 is about 4644.4208465642. The cubic root of 21570645 is about 278.3691118583.

The spelling of 21570645 in words is "twenty-one million, five hundred seventy thousand, six hundred forty-five".