21242537556 has 24 divisors (see below), whose sum is σ = 49571857440. Its totient is φ = 7079997792.

The previous prime is 21242537549. The next prime is 21242537609. The reversal of 21242537556 is 65573524212.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 2830 + ... + 206138.

It is an arithmetic number, because the mean of its divisors is an integer number (2065494060).

Almost surely, 2^21242537556 is an apocalyptic number.

It is an amenable number.

21242537556 is an abundant number, since it is smaller than the sum of its proper divisors (28329319884).

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

21242537556 is a wasteful number, since it uses less digits than its factorization.

21242537556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212023 (or 212021 counting only the distinct ones).

The product of its digits is 504000, while the sum is 42.

The spelling of 21242537556 in words is "twenty-one billion, two hundred forty-two million, five hundred thirty-seven thousand, five hundred fifty-six".