21077522761 has 9 divisors (see below), whose sum is σ = 21610250229. Its totient is φ = 20557629600.

The previous prime is 21077522723. The next prime is 21077522813. The reversal of 21077522761 is 16722577012.

The square root of 21077522761 is 145181.

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 7635439161 + 13442083600 = 87381^2 + 115940^2 .

It is not a de Polignac number, because 21077522761 - 2¹⁹ = 21076998473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21077522461) 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, 5950651 + ... + 5954191.

Almost surely, 2^21077522761 is an apocalyptic number.

21077522761 is the 145181-st square number.

21077522761 is the 72591-st centered octagonal number.

It is an amenable number.

21077522761 is a deficient number, since it is larger than the sum of its proper divisors (532727468).

21077522761 is an frugal number, since it uses more digits than its factorization.

21077522761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7164 (or 3582 counting only the distinct ones).

The product of its (nonzero) digits is 82320, while the sum is 40.

The spelling of 21077522761 in words is "twenty-one billion, seventy-seven million, five hundred twenty-two thousand, seven hundred sixty-one".