21453516779 has 2 divisors, whose sum is σ = 21453516780. Its totient is φ = 21453516778.

The previous prime is 21453516769. The next prime is 21453516827. The reversal of 21453516779 is 97761535412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21453516779 - 2⁸ = 21453516523 is a prime.

It is not a weakly prime, because it can be changed into another prime (21453516709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10726758389 + 10726758390.

It is an arithmetic number, because the mean of its divisors is an integer number (10726758390).

Almost surely, 2^21453516779 is an apocalyptic number.

21453516779 is a deficient number, since it is larger than the sum of its proper divisors (1).

21453516779 is an equidigital number, since it uses as much as digits as its factorization.

21453516779 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1587600, while the sum is 50.

The spelling of 21453516779 in words is "twenty-one billion, four hundred fifty-three million, five hundred sixteen thousand, seven hundred seventy-nine".