66722891 has 2 divisors, whose sum is σ = 66722892. Its totient is φ = 66722890.

The previous prime is 66722861. The next prime is 66722893. The reversal of 66722891 is 19822766.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66722891 - 2⁶ = 66722827 is a prime.

It is a Sophie Germain prime.

Together with 66722893, 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 (66722893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33361445 + 33361446.

It is an arithmetic number, because the mean of its divisors is an integer number (33361446).

Almost surely, 2^66722891 is an apocalyptic number.

66722891 is a deficient number, since it is larger than the sum of its proper divisors (1).

66722891 is an equidigital number, since it uses as much as digits as its factorization.

66722891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 41.

The square root of 66722891 is about 8168.4081068468. The cubic root of 66722891 is about 405.5940902592.

The spelling of 66722891 in words is "sixty-six million, seven hundred twenty-two thousand, eight hundred ninety-one".