21820978840 has 64 divisors (see below), whose sum is σ = 49404168000. Its totient is φ = 8673933312.

The previous prime is 21820978831. The next prime is 21820978867. The reversal of 21820978840 is 4887902812.

It is a congruent 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, 11405724 + ... + 11407636.

It is an arithmetic number, because the mean of its divisors is an integer number (771940125).

Almost surely, 2^21820978840 is an apocalyptic number.

21820978840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21820978840 is an abundant number, since it is smaller than the sum of its proper divisors (27583189160).

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

21820978840 is a wasteful number, since it uses less digits than its factorization.

21820978840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3556 (or 3552 counting only the distinct ones).

The product of its (nonzero) digits is 516096, while the sum is 49.

The spelling of 21820978840 in words is "twenty-one billion, eight hundred twenty million, nine hundred seventy-eight thousand, eight hundred forty".