66840688931 has 2 divisors, whose sum is σ = 66840688932. Its totient is φ = 66840688930.

The previous prime is 66840688921. The next prime is 66840688933. The reversal of 66840688931 is 13988604866.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66840688931 is a prime.

It is a super-2 number, since 2×66840688931² (a number of 22 digits) contains 22 as substring.

Together with 66840688933, 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 (66840688933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33420344465 + 33420344466.

It is an arithmetic number, because the mean of its divisors is an integer number (33420344466).

Almost surely, 2^66840688931 is an apocalyptic number.

66840688931 is a deficient number, since it is larger than the sum of its proper divisors (1).

66840688931 is an equidigital number, since it uses as much as digits as its factorization.

66840688931 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11943936, while the sum is 59.

The spelling of 66840688931 in words is "sixty-six billion, eight hundred forty million, six hundred eighty-eight thousand, nine hundred thirty-one".