21042355679 has 2 divisors, whose sum is σ = 21042355680. Its totient is φ = 21042355678.

The previous prime is 21042355661. The next prime is 21042355721. The reversal of 21042355679 is 97655324012.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21042355679 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21042354679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521177839 + 10521177840.

It is an arithmetic number, because the mean of its divisors is an integer number (10521177840).

Almost surely, 2^21042355679 is an apocalyptic number.

21042355679 is a deficient number, since it is larger than the sum of its proper divisors (1).

21042355679 is an equidigital number, since it uses as much as digits as its factorization.

21042355679 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 453600, while the sum is 44.

The spelling of 21042355679 in words is "twenty-one billion, forty-two million, three hundred fifty-five thousand, six hundred seventy-nine".