667699217 has 2 divisors, whose sum is σ = 667699218. Its totient is φ = 667699216.

The previous prime is 667699213. The next prime is 667699237. The reversal of 667699217 is 712996766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 589712656 + 77986561 = 24284^2 + 8831^2 .

It is a cyclic number.

It is not a de Polignac number, because 667699217 - 2² = 667699213 is a prime.

It is not a weakly prime, because it can be changed into another prime (667699213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333849608 + 333849609.

It is an arithmetic number, because the mean of its divisors is an integer number (333849609).

Almost surely, 2^667699217 is an apocalyptic number.

It is an amenable number.

667699217 is a deficient number, since it is larger than the sum of its proper divisors (1).

667699217 is an equidigital number, since it uses as much as digits as its factorization.

667699217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1714608, while the sum is 53.

The square root of 667699217 is about 25839.8764896429. The cubic root of 667699217 is about 874.0312399923.

The spelling of 667699217 in words is "six hundred sixty-seven million, six hundred ninety-nine thousand, two hundred seventeen".