20456977197721 has 9 divisors (see below), whose sum is σ = 20480972346783. Its totient is φ = 20433010143960.

The previous prime is 20456977197593. The next prime is 20456977197737. The reversal of 20456977197721 is 12779177965402.

The square root of 20456977197721 is 4522939.

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., 9565789165321 + 10891188032400 = 3092861^2 + 3300180^2 .

It is not a de Polignac number, because 20456977197721 - 2⁷ = 20456977197593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20456977197421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4835019676 + ... + 4835023906.

It is an arithmetic number, because the mean of its divisors is an integer number (2275663594087).

Almost surely, 2^{20456977197721} is an apocalyptic number.

20456977197721 is the 4522939-th square number.

20456977197721 is the 2261470-th centered octagonal number.

It is an amenable number.

20456977197721 is a deficient number, since it is larger than the sum of its proper divisors (23995149062).

20456977197721 is an frugal number, since it uses more digits than its factorization.

20456977197721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10600 (or 5300 counting only the distinct ones).

The product of its (nonzero) digits is 93350880, while the sum is 67.

The spelling of 20456977197721 in words is "twenty trillion, four hundred fifty-six billion, nine hundred seventy-seven million, one hundred ninety-seven thousand, seven hundred twenty-one".