667994557 has 2 divisors, whose sum is σ = 667994558. Its totient is φ = 667994556.

The previous prime is 667994539. The next prime is 667994581. The reversal of 667994557 is 755499766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 527666841 + 140327716 = 22971^2 + 11846^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-667994557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (667997557) 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, 333997278 + 333997279.

It is an arithmetic number, because the mean of its divisors is an integer number (333997279).

Almost surely, 2^667994557 is an apocalyptic number.

It is an amenable number.

667994557 is a deficient number, since it is larger than the sum of its proper divisors (1).

667994557 is an equidigital number, since it uses as much as digits as its factorization.

667994557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14288400, while the sum is 58.

The square root of 667994557 is about 25845.5906684293. The cubic root of 667994557 is about 874.1600895946.

The spelling of 667994557 in words is "six hundred sixty-seven million, nine hundred ninety-four thousand, five hundred fifty-seven".