668500081 has 2 divisors, whose sum is σ = 668500082. Its totient is φ = 668500080.

The previous prime is 668500033. The next prime is 668500171. The reversal of 668500081 is 180005866.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 359443681 + 309056400 = 18959^2 + 17580^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668500081 is a prime.

It is a super-2 number, since 2×668500081² = 893784716594013122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (668503081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334250040 + 334250041.

It is an arithmetic number, because the mean of its divisors is an integer number (334250041).

Almost surely, 2^668500081 is an apocalyptic number.

It is an amenable number.

668500081 is a deficient number, since it is larger than the sum of its proper divisors (1).

668500081 is an equidigital number, since it uses as much as digits as its factorization.

668500081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11520, while the sum is 34.

The square root of 668500081 is about 25855.3685141017. The cubic root of 668500081 is about 874.3805492134.

The spelling of 668500081 in words is "six hundred sixty-eight million, five hundred thousand, eighty-one".