666908881 has 2 divisors, whose sum is σ = 666908882. Its totient is φ = 666908880.

The previous prime is 666908863. The next prime is 666908903. The reversal of 666908881 is 188809666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 506025025 + 160883856 = 22495^2 + 12684^2 .

It is a cyclic number.

It is not a de Polignac number, because 666908881 - 2¹⁵ = 666876113 is a prime.

It is a super-2 number, since 2×666908881² = 889534911113344322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (666908581) 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, 333454440 + 333454441.

It is an arithmetic number, because the mean of its divisors is an integer number (333454441).

Almost surely, 2^666908881 is an apocalyptic number.

It is an amenable number.

666908881 is a deficient number, since it is larger than the sum of its proper divisors (1).

666908881 is an equidigital number, since it uses as much as digits as its factorization.

666908881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 995328, while the sum is 52.

The square root of 666908881 is about 25824.5790091533. The cubic root of 666908881 is about 873.6862487811.

The spelling of 666908881 in words is "six hundred sixty-six million, nine hundred eight thousand, eight hundred eighty-one".