21399648642 has 24 divisors (see below), whose sum is σ = 47018949120. Its totient is φ = 7032747960.

The previous prime is 21399648619. The next prime is 21399648649. The reversal of 21399648642 is 24684699312.

21399648642 is a `hidden beast` number, since 2 + 1 + 39 + 96 + 486 + 42 = 666.

It is not an unprimeable number, because it can be changed into a prime (21399648649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8371042 + ... + 8373597.

It is an arithmetic number, because the mean of its divisors is an integer number (1959122880).

Almost surely, 2^21399648642 is an apocalyptic number.

21399648642 is an abundant number, since it is smaller than the sum of its proper divisors (25619300478).

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

21399648642 is a wasteful number, since it uses less digits than its factorization.

21399648642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16744718 (or 16744715 counting only the distinct ones).

The product of its digits is 4478976, while the sum is 54.

The spelling of 21399648642 in words is "twenty-one billion, three hundred ninety-nine million, six hundred forty-eight thousand, six hundred forty-two".