21539837538 has 48 divisors (see below), whose sum is σ = 46843056000. Its totient is φ = 7153323840.

The previous prime is 21539837507. The next prime is 21539837567. The reversal of 21539837538 is 83573893512.

21539837538 is a `hidden beast` number, since 2 + 1 + 539 + 8 + 3 + 75 + 38 = 666.

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 23 ways as a sum of consecutive naturals, for example, 6133203 + ... + 6136713.

It is an arithmetic number, because the mean of its divisors is an integer number (975897000).

Almost surely, 2^21539837538 is an apocalyptic number.

21539837538 is an abundant number, since it is smaller than the sum of its proper divisors (25303218462).

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

21539837538 is a wasteful number, since it uses less digits than its factorization.

21539837538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4687 (or 4684 counting only the distinct ones).

The product of its digits is 5443200, while the sum is 54.

The spelling of 21539837538 in words is "twenty-one billion, five hundred thirty-nine million, eight hundred thirty-seven thousand, five hundred thirty-eight".