21667763771 has 2 divisors, whose sum is σ = 21667763772. Its totient is φ = 21667763770.

The previous prime is 21667763749. The next prime is 21667763773. The reversal of 21667763771 is 17736776612.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21667763771 - 2¹⁸ = 21667501627 is a prime.

Together with 21667763773, 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 (21667763773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10833881885 + 10833881886.

It is an arithmetic number, because the mean of its divisors is an integer number (10833881886).

Almost surely, 2^21667763771 is an apocalyptic number.

21667763771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21667763771 is an equidigital number, since it uses as much as digits as its factorization.

21667763771 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3111696, while the sum is 53.

The spelling of 21667763771 in words is "twenty-one billion, six hundred sixty-seven million, seven hundred sixty-three thousand, seven hundred seventy-one".