21531433550 has 48 divisors (see below), whose sum is σ = 43703452800. Its totient is φ = 7827064800.

The previous prime is 21531433541. The next prime is 21531433591. The reversal of 21531433550 is 5533413512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2844671 + ... + 2852229.

It is an arithmetic number, because the mean of its divisors is an integer number (910488600).

Almost surely, 2^21531433550 is an apocalyptic number.

21531433550 is an abundant number, since it is smaller than the sum of its proper divisors (22172019250).

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

21531433550 is a wasteful number, since it uses less digits than its factorization.

21531433550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12761 (or 12756 counting only the distinct ones).

The product of its (nonzero) digits is 27000, while the sum is 32.

The spelling of 21531433550 in words is "twenty-one billion, five hundred thirty-one million, four hundred thirty-three thousand, five hundred fifty".