21715797563 has 4 divisors (see below), whose sum is σ = 21738025560. Its totient is φ = 21693569568.

The previous prime is 21715797533. The next prime is 21715797611. The reversal of 21715797563 is 36579751712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21715797563 - 2⁸ = 21715797307 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21715797533) 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, 11112533 + ... + 11114486.

It is an arithmetic number, because the mean of its divisors is an integer number (5434506390).

Almost surely, 2^21715797563 is an apocalyptic number.

21715797563 is a deficient number, since it is larger than the sum of its proper divisors (22227997).

21715797563 is an equidigital number, since it uses as much as digits as its factorization.

21715797563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22227996.

The product of its digits is 2778300, while the sum is 53.

The spelling of 21715797563 in words is "twenty-one billion, seven hundred fifteen million, seven hundred ninety-seven thousand, five hundred sixty-three".