21520237530 has 64 divisors (see below), whose sum is σ = 57057177600. Its totient is φ = 5150982720.

The previous prime is 21520237513. The next prime is 21520237561. The reversal of 21520237530 is 3573202512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 386670 + ... + 438809.

It is an arithmetic number, because the mean of its divisors is an integer number (891518400).

Almost surely, 2^21520237530 is an apocalyptic number.

21520237530 is an abundant number, since it is smaller than the sum of its proper divisors (35536940070).

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

21520237530 is a wasteful number, since it uses less digits than its factorization.

21520237530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 825579.

The product of its (nonzero) digits is 12600, while the sum is 30.

The spelling of 21520237530 in words is "twenty-one billion, five hundred twenty million, two hundred thirty-seven thousand, five hundred thirty".