21430617664 has 63 divisors (see below), whose sum is σ = 44113285281. Its totient is φ = 10329419520.

The previous prime is 21430617643. The next prime is 21430617709. The reversal of 21430617664 is 46671603412.

The square root of 21430617664 is 146392.

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., 11237696064 + 10192921600 = 106008^2 + 100960^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 33962629 + ... + 33963259.

Almost surely, 2^21430617664 is an apocalyptic number.

21430617664 is the 146392-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21430617664

21430617664 is an abundant number, since it is smaller than the sum of its proper divisors (22682667617).

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

21430617664 is an frugal number, since it uses more digits than its factorization.

21430617664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1332 (or 662 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 40.

The spelling of 21430617664 in words is "twenty-one billion, four hundred thirty million, six hundred seventeen thousand, six hundred sixty-four".