21108796213761 has 9 divisors (see below), whose sum is σ = 30490503329091. Its totient is φ = 14072521620312.

The previous prime is 21108796213741. The next prime is 21108796213783. The reversal of 21108796213761 is 16731269780112.

The square root of 21108796213761 is 4594431.

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

21108796213761 is a `hidden beast` number, since 2 + 1 + 1 + 0 + 8 + 7 + 9 + 621 + 3 + 7 + 6 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 5716952730225 + 15391843483536 = 2391015^2 + 3923244^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 21108796213761 - 2¹⁵ = 21108796180993 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21108796213698 and 21108796213707.

It is not an unprimeable number, because it can be changed into a prime (21108796213711) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 13017555 + ... + 14549031.

Almost surely, 2^{21108796213761} is an apocalyptic number.

21108796213761 is the 4594431-st square number.

21108796213761 is the 2297216-th centered octagonal number.

It is an amenable number.

21108796213761 is a deficient number, since it is larger than the sum of its proper divisors (9381707115330).

21108796213761 is an frugal number, since it uses more digits than its factorization.

21108796213761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3062960 (or 1531480 counting only the distinct ones).

The product of its (nonzero) digits is 1524096, while the sum is 54.

The spelling of 21108796213761 in words is "twenty-one trillion, one hundred eight billion, seven hundred ninety-six million, two hundred thirteen thousand, seven hundred sixty-one".