21636963761 has 16 divisors (see below), whose sum is σ = 25242134400. Its totient is φ = 18538969680.

The previous prime is 21636963721. The next prime is 21636963769. The reversal of 21636963761 is 16736963612.

It is not a de Polignac number, because 21636963761 - 2¹⁸ = 21636701617 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21636963769) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1031306 + ... + 1052076.

It is an arithmetic number, because the mean of its divisors is an integer number (1577633400).

Almost surely, 2^21636963761 is an apocalyptic number.

It is an amenable number.

21636963761 is a deficient number, since it is larger than the sum of its proper divisors (3605170639).

21636963761 is an equidigital number, since it uses as much as digits as its factorization.

21636963761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23829 (or 23815 counting only the distinct ones).

The product of its digits is 1469664, while the sum is 50.

The spelling of 21636963761 in words is "twenty-one billion, six hundred thirty-six million, nine hundred sixty-three thousand, seven hundred sixty-one".