21653565001 has 2 divisors, whose sum is σ = 21653565002. Its totient is φ = 21653565000.

The previous prime is 21653564993. The next prime is 21653565029. The reversal of 21653565001 is 10056535612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14651892025 + 7001672976 = 121045^2 + 83676^2 .

It is a cyclic number.

It is not a de Polignac number, because 21653565001 - 2³ = 21653564993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21653565071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10826782500 + 10826782501.

It is an arithmetic number, because the mean of its divisors is an integer number (10826782501).

Almost surely, 2^21653565001 is an apocalyptic number.

It is an amenable number.

21653565001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21653565001 is an equidigital number, since it uses as much as digits as its factorization.

21653565001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27000, while the sum is 34.

The spelling of 21653565001 in words is "twenty-one billion, six hundred fifty-three million, five hundred sixty-five thousand, one".