21678716359 has 4 divisors (see below), whose sum is σ = 21736836616. Its totient is φ = 21620596104.

The previous prime is 21678716329. The next prime is 21678716393. The reversal of 21678716359 is 95361787612.

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 21678716359 - 2²⁵ = 21645161927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678716329) 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, 29059569 + ... + 29060314.

It is an arithmetic number, because the mean of its divisors is an integer number (5434209154).

Almost surely, 2^21678716359 is an apocalyptic number.

21678716359 is a deficient number, since it is larger than the sum of its proper divisors (58120257).

21678716359 is an equidigital number, since it uses as much as digits as its factorization.

21678716359 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58120256.

The product of its digits is 3810240, while the sum is 55.

The spelling of 21678716359 in words is "twenty-one billion, six hundred seventy-eight million, seven hundred sixteen thousand, three hundred fifty-nine".