21540302779 has 2 divisors, whose sum is σ = 21540302780. Its totient is φ = 21540302778.

The previous prime is 21540302767. The next prime is 21540302789. The reversal of 21540302779 is 97720304512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21540302779 - 2⁵ = 21540302747 is a prime.

It is not a weakly prime, because it can be changed into another prime (21540302789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10770151389 + 10770151390.

It is an arithmetic number, because the mean of its divisors is an integer number (10770151390).

Almost surely, 2^21540302779 is an apocalyptic number.

21540302779 is a deficient number, since it is larger than the sum of its proper divisors (1).

21540302779 is an equidigital number, since it uses as much as digits as its factorization.

21540302779 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 105840, while the sum is 40.

The spelling of 21540302779 in words is "twenty-one billion, five hundred forty million, three hundred two thousand, seven hundred seventy-nine".