667767817 has 2 divisors, whose sum is σ = 667767818. Its totient is φ = 667767816.

The previous prime is 667767811. The next prime is 667767827. The reversal of 667767817 is 718767766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 662084361 + 5683456 = 25731^2 + 2384^2 .

It is a cyclic number.

It is not a de Polignac number, because 667767817 - 2²⁷ = 533550089 is a prime.

It is a super-5 number, since 5×667767817⁵ (a number of 45 digits) contains 55555 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (667767811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333883908 + 333883909.

It is an arithmetic number, because the mean of its divisors is an integer number (333883909).

Almost surely, 2^667767817 is an apocalyptic number.

It is an amenable number.

667767817 is a deficient number, since it is larger than the sum of its proper divisors (1).

667767817 is an equidigital number, since it uses as much as digits as its factorization.

667767817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4148928, while the sum is 55.

The square root of 667767817 is about 25841.2038612755. The cubic root of 667767817 is about 874.0611718779.

The spelling of 667767817 in words is "six hundred sixty-seven million, seven hundred sixty-seven thousand, eight hundred seventeen".