20988410478721 has 27 divisors (see below), whose sum is σ = 24568432376769. Its totient is φ = 17877778192008.

The previous prime is 20988410478647. The next prime is 20988410478769. The reversal of 20988410478721 is 12787401488902.

The square root of 20988410478721 is 4581311.

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

It is not a de Polignac number, because 20988410478721 - 2¹³ = 20988410470529 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20988410478721.

It is not an unprimeable number, because it can be changed into a prime (20988410478421) by changing a digit.

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 26 ways as a sum of consecutive naturals, for example, 5355550600 + ... + 5355554518.

Almost surely, 2^{20988410478721} is an apocalyptic number.

20988410478721 is the 4581311-st square number.

20988410478721 is the 2290656-th centered octagonal number.

It is an amenable number.

20988410478721 is a deficient number, since it is larger than the sum of its proper divisors (3580021898048).

20988410478721 is an frugal number, since it uses more digits than its factorization.

20988410478721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8186 (or 4093 counting only the distinct ones).

The product of its (nonzero) digits is 14450688, while the sum is 61.

The spelling of 20988410478721 in words is "twenty trillion, nine hundred eighty-eight billion, four hundred ten million, four hundred seventy-eight thousand, seven hundred twenty-one".