21277765667 has 2 divisors, whose sum is σ = 21277765668. Its totient is φ = 21277765666.

The previous prime is 21277765609. The next prime is 21277765669. The reversal of 21277765667 is 76656777212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21277765667 - 2²⁸ = 21009330211 is a prime.

Together with 21277765669, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21277765669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10638882833 + 10638882834.

It is an arithmetic number, because the mean of its divisors is an integer number (10638882834).

Almost surely, 2^21277765667 is an apocalyptic number.

21277765667 is a deficient number, since it is larger than the sum of its proper divisors (1).

21277765667 is an equidigital number, since it uses as much as digits as its factorization.

21277765667 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10372320, while the sum is 56.

The spelling of 21277765667 in words is "twenty-one billion, two hundred seventy-seven million, seven hundred sixty-five thousand, six hundred sixty-seven".