21999656640 has 112 divisors (see below), whose sum is σ = 75221945568. Its totient is φ = 5415297024.

The previous prime is 21999656587. The next prime is 21999656827. The reversal of 21999656640 is 4665699912.

It is a happy 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, 868917 + ... + 893876.

It is an arithmetic number, because the mean of its divisors is an integer number (671624514).

Almost surely, 2^21999656640 is an apocalyptic number.

21999656640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21999656640 is an abundant number, since it is smaller than the sum of its proper divisors (53222288928).

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

21999656640 is a wasteful number, since it uses less digits than its factorization.

21999656640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1762826 (or 1762816 counting only the distinct ones).

The product of its (nonzero) digits is 6298560, while the sum is 57.

The spelling of 21999656640 in words is "twenty-one billion, nine hundred ninety-nine million, six hundred fifty-six thousand, six hundred forty".