21908516 has 48 divisors (see below), whose sum is σ = 45330432. Its totient is φ = 9072000.

The previous prime is 21908503. The next prime is 21908519. The reversal of 21908516 is 61580912.

It is not an unprimeable number, because it can be changed into a prime (21908519) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 172445 + ... + 172571.

It is an arithmetic number, because the mean of its divisors is an integer number (944384).

Almost surely, 2^21908516 is an apocalyptic number.

It is an amenable number.

21908516 is an abundant number, since it is smaller than the sum of its proper divisors (23421916).

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

21908516 is a wasteful number, since it uses less digits than its factorization.

21908516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 300 (or 298 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 21908516 is about 4680.6533731948. The cubic root of 21908516 is about 279.8149968382.

The spelling of 21908516 in words is "twenty-one million, nine hundred eight thousand, five hundred sixteen".