21813907679 has 2 divisors, whose sum is σ = 21813907680. Its totient is φ = 21813907678.

The previous prime is 21813907673. The next prime is 21813907711. The reversal of 21813907679 is 97670931812.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21813907679 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21813907679.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21813907673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10906953839 + 10906953840.

It is an arithmetic number, because the mean of its divisors is an integer number (10906953840).

Almost surely, 2^21813907679 is an apocalyptic number.

21813907679 is a deficient number, since it is larger than the sum of its proper divisors (1).

21813907679 is an equidigital number, since it uses as much as digits as its factorization.

21813907679 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1143072, while the sum is 53.

The spelling of 21813907679 in words is "twenty-one billion, eight hundred thirteen million, nine hundred seven thousand, six hundred seventy-nine".