667789217 has 2 divisors, whose sum is σ = 667789218. Its totient is φ = 667789216.

The previous prime is 667789147. The next prime is 667789231. The reversal of 667789217 is 712987766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 659256976 + 8532241 = 25676^2 + 2921^2 .

It is a cyclic number.

It is not a de Polignac number, because 667789217 - 2¹⁸ = 667527073 is a prime.

It is not a weakly prime, because it can be changed into another prime (667789267) 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, 333894608 + 333894609.

It is an arithmetic number, because the mean of its divisors is an integer number (333894609).

Almost surely, 2^667789217 is an apocalyptic number.

It is an amenable number.

667789217 is a deficient number, since it is larger than the sum of its proper divisors (1).

667789217 is an equidigital number, since it uses as much as digits as its factorization.

667789217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1778112, while the sum is 53.

The square root of 667789217 is about 25841.6179253544. The cubic root of 667789217 is about 874.0705088105.

The spelling of 667789217 in words is "six hundred sixty-seven million, seven hundred eighty-nine thousand, two hundred seventeen".