21438351924 has 24 divisors (see below), whose sum is σ = 54570350688. Its totient is φ = 6496470240.

The previous prime is 21438351899. The next prime is 21438351931. The reversal of 21438351924 is 42915383412.

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, 81205747 + ... + 81206010.

It is an arithmetic number, because the mean of its divisors is an integer number (2273764612).

Almost surely, 2^21438351924 is an apocalyptic number.

It is an amenable number.

21438351924 is an abundant number, since it is smaller than the sum of its proper divisors (33131998764).

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

21438351924 is a wasteful number, since it uses less digits than its factorization.

21438351924 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162411775 (or 162411773 counting only the distinct ones).

The product of its digits is 207360, while the sum is 42.

The spelling of 21438351924 in words is "twenty-one billion, four hundred thirty-eight million, three hundred fifty-one thousand, nine hundred twenty-four".