21710816563 has 4 divisors (see below), whose sum is σ = 22459465440. Its totient is φ = 20962167688.

The previous prime is 21710816537. The next prime is 21710816587. The reversal of 21710816563 is 36561801712.

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 21710816563 - 2⁵ = 21710816531 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21710816513) 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, 374324395 + ... + 374324452.

It is an arithmetic number, because the mean of its divisors is an integer number (5614866360).

Almost surely, 2^21710816563 is an apocalyptic number.

21710816563 is a deficient number, since it is larger than the sum of its proper divisors (748648877).

21710816563 is an equidigital number, since it uses as much as digits as its factorization.

21710816563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 748648876.

The product of its (nonzero) digits is 60480, while the sum is 40.

The spelling of 21710816563 in words is "twenty-one billion, seven hundred ten million, eight hundred sixteen thousand, five hundred sixty-three".