21529105984 has 21 divisors (see below), whose sum is σ = 42724149121. Its totient is φ = 10763966080.

The previous prime is 21529105981. The next prime is 21529105993. The reversal of 21529105984 is 48950192512.

It is a happy number.

The square root of 21529105984 is 146728.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 2196984384 + 19332121600 = 46872^2 + 139040^2 .

It is a Smith number, since the sum of its digits (46) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21529105981) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1164654 + ... + 1182994.

Almost surely, 2^21529105984 is an apocalyptic number.

21529105984 is the 146728-th square number.

It is an amenable number.

21529105984 is a deficient number, since it is larger than the sum of its proper divisors (21195043137).

21529105984 is an frugal number, since it uses more digits than its factorization.

21529105984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36694 (or 18343 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 46.

The spelling of 21529105984 in words is "twenty-one billion, five hundred twenty-nine million, one hundred five thousand, nine hundred eighty-four".