21581960464 has 45 divisors (see below), whose sum is σ = 44154514053. Its totient is φ = 10217745216.

The previous prime is 21581960443. The next prime is 21581960489. The reversal of 21581960464 is 46406918512.

It is a happy number.

The square root of 21581960464 is 146908.

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., 14694288400 + 6887672064 = 121220^2 + 82992^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 11164042 + ... + 11165974.

Almost surely, 2^21581960464 is an apocalyptic number.

21581960464 is the 146908-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21581960464

21581960464 is an abundant number, since it is smaller than the sum of its proper divisors (22572553589).

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

21581960464 is an frugal number, since it uses more digits than its factorization.

21581960464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3912 (or 1954 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 46.

The spelling of 21581960464 in words is "twenty-one billion, five hundred eighty-one million, nine hundred sixty thousand, four hundred sixty-four".