21131523530 has 16 divisors (see below), whose sum is σ = 40962645864. Its totient is φ = 7802408640.

The previous prime is 21131523503. The next prime is 21131523547. The reversal of 21131523530 is 3532513112.

It can be written as a sum of positive squares in 4 ways, for example, as 13259752801 + 7871770729 = 115151^2 + 88723^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 21131523530.

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, 81274961 + ... + 81275220.

Almost surely, 2^21131523530 is an apocalyptic number.

21131523530 is a deficient number, since it is larger than the sum of its proper divisors (19831122334).

21131523530 is a wasteful number, since it uses less digits than its factorization.

21131523530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162550201.

The product of its (nonzero) digits is 2700, while the sum is 26.

The spelling of 21131523530 in words is "twenty-one billion, one hundred thirty-one million, five hundred twenty-three thousand, five hundred thirty".