20993880920464 has 135 divisors (see below), whose sum is σ = 44265555110817. Its totient is φ = 9643560095232.

The previous prime is 20993880920461. The next prime is 20993880920473. The reversal of 20993880920464 is 46402908839902.

The square root of 20993880920464 is 4581908.

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., 16344716979600 + 4649163940864 = 4042860^2 + 2156192^2 .

It is a super-2 number, since 2×20993880920464² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20993880920396 and 20993880920405.

It is not an unprimeable number, because it can be changed into a prime (20993880920461) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 13397498209 + ... + 13397499775.

Almost surely, 2^{20993880920464} is an apocalyptic number.

20993880920464 is the 4581908-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20993880920464

20993880920464 is an abundant number, since it is smaller than the sum of its proper divisors (23271674190353).

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

20993880920464 is an frugal number, since it uses more digits than its factorization.

20993880920464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3262 (or 1629 counting only the distinct ones).

The product of its (nonzero) digits is 53747712, while the sum is 64.

The spelling of 20993880920464 in words is "twenty trillion, nine hundred ninety-three billion, eight hundred eighty million, nine hundred twenty thousand, four hundred sixty-four".