21455760761 has 4 divisors (see below), whose sum is σ = 21478562724. Its totient is φ = 21432958800.

The previous prime is 21455760743. The next prime is 21455760769. The reversal of 21455760761 is 16706755412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6198570361 + 15257190400 = 78731^2 + 123520^2 .

It is a cyclic number.

It is not a de Polignac number, because 21455760761 - 2²² = 21451566457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21455760769) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11399570 + ... + 11401451.

It is an arithmetic number, because the mean of its divisors is an integer number (5369640681).

Almost surely, 2^21455760761 is an apocalyptic number.

It is an amenable number.

21455760761 is a deficient number, since it is larger than the sum of its proper divisors (22801963).

21455760761 is an equidigital number, since it uses as much as digits as its factorization.

21455760761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22801962.

The product of its (nonzero) digits is 352800, while the sum is 44.

The spelling of 21455760761 in words is "twenty-one billion, four hundred fifty-five million, seven hundred sixty thousand, seven hundred sixty-one".