21275320265 has 4 divisors (see below), whose sum is σ = 25530384324. Its totient is φ = 17020256208.

The previous prime is 21275320193. The next prime is 21275320271. The reversal of 21275320265 is 56202357212.

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 6249218704 + 15026101561 = 79052^2 + 122581^2 .

It is a cyclic number.

It is not a de Polignac number, because 21275320265 - 2¹⁶ = 21275254729 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2127532022 + ... + 2127532031.

It is an arithmetic number, because the mean of its divisors is an integer number (6382596081).

Almost surely, 2^21275320265 is an apocalyptic number.

It is an amenable number.

21275320265 is a deficient number, since it is larger than the sum of its proper divisors (4255064059).

21275320265 is an equidigital number, since it uses as much as digits as its factorization.

21275320265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4255064058.

The product of its (nonzero) digits is 50400, while the sum is 35.

Adding to 21275320265 its reverse (56202357212), we get a palindrome (77477677477).

The spelling of 21275320265 in words is "twenty-one billion, two hundred seventy-five million, three hundred twenty thousand, two hundred sixty-five".