21613640 has 32 divisors (see below), whose sum is σ = 51192000. Its totient is φ = 8190144.

The previous prime is 21613639. The next prime is 21613663. The reversal of 21613640 is 4631612.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13460 + ... + 14979.

It is an arithmetic number, because the mean of its divisors is an integer number (1599750).

Almost surely, 2^21613640 is an apocalyptic number.

21613640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21613640 is an abundant number, since it is smaller than the sum of its proper divisors (29578360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21613640 is a wasteful number, since it uses less digits than its factorization.

21613640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28469 (or 28465 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21613640 is about 4649.0472142150. The cubic root of 21613640 is about 278.5539392295.

The spelling of 21613640 in words is "twenty-one million, six hundred thirteen thousand, six hundred forty".