21670972091 has 2 divisors, whose sum is σ = 21670972092. Its totient is φ = 21670972090.

The previous prime is 21670972079. The next prime is 21670972093. The reversal of 21670972091 is 19027907612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21670972091 - 2⁶ = 21670972027 is a prime.

Together with 21670972093, 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 (21670972093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10835486045 + 10835486046.

It is an arithmetic number, because the mean of its divisors is an integer number (10835486046).

Almost surely, 2^21670972091 is an apocalyptic number.

21670972091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21670972091 is an equidigital number, since it uses as much as digits as its factorization.

21670972091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 95256, while the sum is 44.

The spelling of 21670972091 in words is "twenty-one billion, six hundred seventy million, nine hundred seventy-two thousand, ninety-one".