666294581 has 2 divisors, whose sum is σ = 666294582. Its totient is φ = 666294580.

The previous prime is 666294569. The next prime is 666294623. The reversal of 666294581 is 185492666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 653262481 + 13032100 = 25559^2 + 3610^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666294581 is a prime.

It is a super-2 number, since 2×666294581² = 887896937339931122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666294511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333147290 + 333147291.

It is an arithmetic number, because the mean of its divisors is an integer number (333147291).

Almost surely, 2^666294581 is an apocalyptic number.

It is an amenable number.

666294581 is a deficient number, since it is larger than the sum of its proper divisors (1).

666294581 is an equidigital number, since it uses as much as digits as its factorization.

666294581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 622080, while the sum is 47.

The square root of 666294581 is about 25812.6825610978. The cubic root of 666294581 is about 873.4179111058.

The spelling of 666294581 in words is "six hundred sixty-six million, two hundred ninety-four thousand, five hundred eighty-one".