21640345927 has 2 divisors, whose sum is σ = 21640345928. Its totient is φ = 21640345926.

The previous prime is 21640345913. The next prime is 21640345931. The reversal of 21640345927 is 72954304612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21640345927 - 2¹⁵ = 21640313159 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21640345957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10820172963 + 10820172964.

It is an arithmetic number, because the mean of its divisors is an integer number (10820172964).

Almost surely, 2^21640345927 is an apocalyptic number.

21640345927 is a deficient number, since it is larger than the sum of its proper divisors (1).

21640345927 is an equidigital number, since it uses as much as digits as its factorization.

21640345927 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 362880, while the sum is 43.

The spelling of 21640345927 in words is "twenty-one billion, six hundred forty million, three hundred forty-five thousand, nine hundred twenty-seven".