666215923 has 2 divisors, whose sum is σ = 666215924. Its totient is φ = 666215922.

The previous prime is 666215917. The next prime is 666215987. The reversal of 666215923 is 329512666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 666215923 - 2²⁹ = 129345011 is a prime.

It is not a weakly prime, because it can be changed into another prime (666215993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333107961 + 333107962.

It is an arithmetic number, because the mean of its divisors is an integer number (333107962).

Almost surely, 2^666215923 is an apocalyptic number.

666215923 is a deficient number, since it is larger than the sum of its proper divisors (1).

666215923 is an equidigital number, since it uses as much as digits as its factorization.

666215923 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 116640, while the sum is 40.

The square root of 666215923 is about 25811.1588852574. The cubic root of 666215923 is about 873.3835399174.

The spelling of 666215923 in words is "six hundred sixty-six million, two hundred fifteen thousand, nine hundred twenty-three".