21531027990 has 32 divisors (see below), whose sum is σ = 53341387776. Its totient is φ = 5556394080.

The previous prime is 21531027977. The next prime is 21531028031. The reversal of 21531027990 is 9972013512.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11574892 + ... + 11576751.

It is an arithmetic number, because the mean of its divisors is an integer number (1666918368).

Almost surely, 2^21531027990 is an apocalyptic number.

21531027990 is an abundant number, since it is smaller than the sum of its proper divisors (31810359786).

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

21531027990 is a wasteful number, since it uses less digits than its factorization.

21531027990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23151684.

The product of its (nonzero) digits is 34020, while the sum is 39.

The spelling of 21531027990 in words is "twenty-one billion, five hundred thirty-one million, twenty-seven thousand, nine hundred ninety".