666944431 has 2 divisors, whose sum is σ = 666944432. Its totient is φ = 666944430.

The previous prime is 666944371. The next prime is 666944461. The reversal of 666944431 is 134449666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666944431 - 2⁷ = 666944303 is a prime.

It is a super-2 number, since 2×666944431² = 889629748083827522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666944461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333472215 + 333472216.

It is an arithmetic number, because the mean of its divisors is an integer number (333472216).

Almost surely, 2^666944431 is an apocalyptic number.

666944431 is a deficient number, since it is larger than the sum of its proper divisors (1).

666944431 is an equidigital number, since it uses as much as digits as its factorization.

666944431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 43.

The square root of 666944431 is about 25825.2672977454. The cubic root of 666944431 is about 873.7017726381.

The spelling of 666944431 in words is "six hundred sixty-six million, nine hundred forty-four thousand, four hundred thirty-one".