21640516 has 24 divisors (see below), whose sum is σ = 40086144. Its totient is φ = 10200960.

The previous prime is 21640513. The next prime is 21640529. The reversal of 21640516 is 61504612.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21640513) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4876 + ... + 8188.

It is an arithmetic number, because the mean of its divisors is an integer number (1670256).

Almost surely, 2^21640516 is an apocalyptic number.

It is an amenable number.

21640516 is a deficient number, since it is larger than the sum of its proper divisors (18445628).

21640516 is a wasteful number, since it uses less digits than its factorization.

21640516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3411 (or 3409 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21640516 is about 4651.9368009465. The cubic root of 21640516 is about 278.6693496024.

The spelling of 21640516 in words is "twenty-one million, six hundred forty thousand, five hundred sixteen".