21153819572 has 18 divisors (see below), whose sum is σ = 37493757378. Its totient is φ = 10443012528.

The previous prime is 21153819571. The next prime is 21153819581. The reversal of 21153819572 is 27591835112.

It can be written as a sum of positive squares in only one way, i.e., 18549350416 + 2604469156 = 136196^2 + 51034^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21153819571) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 398723 + ... + 448650.

It is an arithmetic number, because the mean of its divisors is an integer number (2082986521).

Almost surely, 2^21153819572 is an apocalyptic number.

It is an amenable number.

21153819572 is a deficient number, since it is larger than the sum of its proper divisors (16339937806).

21153819572 is an equidigital number, since it uses as much as digits as its factorization.

21153819572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 847535 (or 847454 counting only the distinct ones).

The product of its digits is 151200, while the sum is 44.

The spelling of 21153819572 in words is "twenty-one billion, one hundred fifty-three million, eight hundred nineteen thousand, five hundred seventy-two".