21399905440 has 48 divisors (see below), whose sum is σ = 50678097120. Its totient is φ = 8539505920.

The previous prime is 21399905383. The next prime is 21399905477. The reversal of 21399905440 is 4450999312.

It is a Smith number, since the sum of its digits (46) coincides with the sum of the digits of its prime factors.

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, 92566 + ... + 226645.

It is an arithmetic number, because the mean of its divisors is an integer number (1055793690).

Almost surely, 2^21399905440 is an apocalyptic number.

21399905440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21399905440 is an abundant number, since it is smaller than the sum of its proper divisors (29278191680).

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

21399905440 is a wasteful number, since it uses less digits than its factorization.

21399905440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319645 (or 319637 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 46.

The spelling of 21399905440 in words is "twenty-one billion, three hundred ninety-nine million, nine hundred five thousand, four hundred forty".