21908516518 has 16 divisors (see below), whose sum is σ = 38323936800. Its totient is φ = 9389363928.

The previous prime is 21908516449. The next prime is 21908516533. The reversal of 21908516518 is 81561580912.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15967621 + ... + 15968992.

It is an arithmetic number, because the mean of its divisors is an integer number (2395246050).

Almost surely, 2^21908516518 is an apocalyptic number.

21908516518 is a deficient number, since it is larger than the sum of its proper divisors (16415420282).

21908516518 is an equidigital number, since it uses as much as digits as its factorization.

21908516518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31936636 (or 31936622 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 46.

The spelling of 21908516518 in words is "twenty-one billion, nine hundred eight million, five hundred sixteen thousand, five hundred eighteen".