666791963 has 2 divisors, whose sum is σ = 666791964. Its totient is φ = 666791962.

The previous prime is 666791959. The next prime is 666791987. The reversal of 666791963 is 369197666.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 666791963 - 2² = 666791959 is a prime.

It is a super-2 number, since 2×666791963² = 889223043842786738, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (666791933) 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, 333395981 + 333395982.

It is an arithmetic number, because the mean of its divisors is an integer number (333395982).

Almost surely, 2^666791963 is an apocalyptic number.

666791963 is a deficient number, since it is larger than the sum of its proper divisors (1).

666791963 is an equidigital number, since it uses as much as digits as its factorization.

666791963 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2204496, while the sum is 53.

The square root of 666791963 is about 25822.3152137836. The cubic root of 666791963 is about 873.6351895226.

The spelling of 666791963 in words is "six hundred sixty-six million, seven hundred ninety-one thousand, nine hundred sixty-three".