21776609761 has 9 divisors (see below), whose sum is σ = 21928921689. Its totient is φ = 21625351536.

The previous prime is 21776609759. The next prime is 21776609807. The reversal of 21776609761 is 16790667712.

The square root of 21776609761 is 147569.

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

It can be written as a sum of positive squares in 4 ways, for example, as 85211361 + 21691398400 = 9231^2 + 147280^2 .

It is not a de Polignac number, because 21776609761 - 2¹ = 21776609759 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21776609699 and 21776609708.

It is not an unprimeable number, because it can be changed into a prime (21776609861) 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, 25529011 + ... + 25529863.

Almost surely, 2^21776609761 is an apocalyptic number.

21776609761 is the 147569-th square number.

21776609761 is the 73785-th centered octagonal number.

It is an amenable number.

21776609761 is a deficient number, since it is larger than the sum of its proper divisors (152311928).

21776609761 is an frugal number, since it uses more digits than its factorization.

21776609761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2052 (or 1026 counting only the distinct ones).

The product of its (nonzero) digits is 1333584, while the sum is 52.

The spelling of 21776609761 in words is "twenty-one billion, seven hundred seventy-six million, six hundred nine thousand, seven hundred sixty-one".