666320731 has 2 divisors, whose sum is σ = 666320732. Its totient is φ = 666320730.

The previous prime is 666320687. The next prime is 666320749. The reversal of 666320731 is 137023666.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666320731 is a prime.

It is a super-2 number, since 2×666320731² = 887966633120748722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (666320771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333160365 + 333160366.

It is an arithmetic number, because the mean of its divisors is an integer number (333160366).

Almost surely, 2^666320731 is an apocalyptic number.

666320731 is a deficient number, since it is larger than the sum of its proper divisors (1).

666320731 is an equidigital number, since it uses as much as digits as its factorization.

666320731 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27216, while the sum is 34.

The square root of 666320731 is about 25813.1890900756. The cubic root of 666320731 is about 873.4293372729.

The spelling of 666320731 in words is "six hundred sixty-six million, three hundred twenty thousand, seven hundred thirty-one".