21091779679 has 2 divisors, whose sum is σ = 21091779680. Its totient is φ = 21091779678.

The previous prime is 21091779661. The next prime is 21091779701. The reversal of 21091779679 is 97697719012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21091779679 - 2⁵ = 21091779647 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21091779479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10545889839 + 10545889840.

It is an arithmetic number, because the mean of its divisors is an integer number (10545889840).

Almost surely, 2^21091779679 is an apocalyptic number.

21091779679 is a deficient number, since it is larger than the sum of its proper divisors (1).

21091779679 is an equidigital number, since it uses as much as digits as its factorization.

21091779679 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3000564, while the sum is 58.

The spelling of 21091779679 in words is "twenty-one billion, ninety-one million, seven hundred seventy-nine thousand, six hundred seventy-nine".