21640768027 has 2 divisors, whose sum is σ = 21640768028. Its totient is φ = 21640768026.

The previous prime is 21640767983. The next prime is 21640768091. The reversal of 21640768027 is 72086704612.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21640768027 is a prime.

It is not a weakly prime, because it can be changed into another prime (21640768427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10820384013 + 10820384014.

It is an arithmetic number, because the mean of its divisors is an integer number (10820384014).

Almost surely, 2^21640768027 is an apocalyptic number.

21640768027 is a deficient number, since it is larger than the sum of its proper divisors (1).

21640768027 is an equidigital number, since it uses as much as digits as its factorization.

21640768027 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 225792, while the sum is 43.

The spelling of 21640768027 in words is "twenty-one billion, six hundred forty million, seven hundred sixty-eight thousand, twenty-seven".