21816687313 has 4 divisors (see below), whose sum is σ = 21832283200. Its totient is φ = 21801091428.

The previous prime is 21816687301. The next prime is 21816687331. The reversal of 21816687313 is 31378661812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21816687313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21816682313) 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, 7795845 + ... + 7798642.

It is an arithmetic number, because the mean of its divisors is an integer number (5458070800).

Almost surely, 2^21816687313 is an apocalyptic number.

It is an amenable number.

21816687313 is a deficient number, since it is larger than the sum of its proper divisors (15595887).

21816687313 is a wasteful number, since it uses less digits than its factorization.

21816687313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15595886.

The product of its digits is 290304, while the sum is 46.

The spelling of 21816687313 in words is "twenty-one billion, eight hundred sixteen million, six hundred eighty-seven thousand, three hundred thirteen".