21653913601 has 2 divisors, whose sum is σ = 21653913602. Its totient is φ = 21653913600.

The previous prime is 21653913599. The next prime is 21653913623. The reversal of 21653913601 is 10631935612.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18576327025 + 3077586576 = 136295^2 + 55476^2 .

It is a cyclic number.

It is not a de Polignac number, because 21653913601 - 2¹ = 21653913599 is a prime.

Together with 21653913599, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21653913101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10826956800 + 10826956801.

It is an arithmetic number, because the mean of its divisors is an integer number (10826956801).

Almost surely, 2^21653913601 is an apocalyptic number.

It is an amenable number.

21653913601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21653913601 is an equidigital number, since it uses as much as digits as its factorization.

21653913601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 29160, while the sum is 37.

The spelling of 21653913601 in words is "twenty-one billion, six hundred fifty-three million, nine hundred thirteen thousand, six hundred one".