667644959 has 2 divisors, whose sum is σ = 667644960. Its totient is φ = 667644958.

The previous prime is 667644953. The next prime is 667644997. The reversal of 667644959 is 959446766.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-667644959 is a prime.

It is a super-2 number, since 2×667644959² = 891499582556223362, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (667644953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333822479 + 333822480.

It is an arithmetic number, because the mean of its divisors is an integer number (333822480).

Almost surely, 2^667644959 is an apocalyptic number.

667644959 is a deficient number, since it is larger than the sum of its proper divisors (1).

667644959 is an equidigital number, since it uses as much as digits as its factorization.

667644959 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9797760, while the sum is 56.

The square root of 667644959 is about 25838.8265793940. The cubic root of 667644959 is about 874.0075644258.

The spelling of 667644959 in words is "six hundred sixty-seven million, six hundred forty-four thousand, nine hundred fifty-nine".