21631130065 has 4 divisors (see below), whose sum is σ = 25957356084. Its totient is φ = 17304904048.

The previous prime is 21631130063. The next prime is 21631130071. The reversal of 21631130065 is 56003113612.

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 12040453441 + 9590676624 = 109729^2 + 97932^2 .

It is a cyclic number.

It is not a de Polignac number, because 21631130065 - 2¹ = 21631130063 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21631130063) 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, 2163113002 + ... + 2163113011.

It is an arithmetic number, because the mean of its divisors is an integer number (6489339021).

Almost surely, 2^21631130065 is an apocalyptic number.

It is an amenable number.

21631130065 is a deficient number, since it is larger than the sum of its proper divisors (4326226019).

21631130065 is an equidigital number, since it uses as much as digits as its factorization.

21631130065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4326226018.

The product of its (nonzero) digits is 3240, while the sum is 28.

Adding to 21631130065 its reverse (56003113612), we get a palindrome (77634243677).

The spelling of 21631130065 in words is "twenty-one billion, six hundred thirty-one million, one hundred thirty thousand, sixty-five".