6665881 has 2 divisors, whose sum is σ = 6665882. Its totient is φ = 6665880.

The previous prime is 6665873. The next prime is 6665909. The reversal of 6665881 is 1885666.

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., 5475600 + 1190281 = 2340^2 + 1091^2 .

It is a cyclic number.

It is not a de Polignac number, because 6665881 - 2³ = 6665873 is a prime.

It is a super-2 number, since 2×6665881² = 88867939012322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (6665801) 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, 3332940 + 3332941.

It is an arithmetic number, because the mean of its divisors is an integer number (3332941).

Almost surely, 2^6665881 is an apocalyptic number.

It is an amenable number.

6665881 is a deficient number, since it is larger than the sum of its proper divisors (1).

6665881 is an equidigital number, since it uses as much as digits as its factorization.

6665881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69120, while the sum is 40.

The square root of 6665881 is about 2581.8367492930. The cubic root of 6665881 is about 188.1998120793.

The spelling of 6665881 in words is "six million, six hundred sixty-five thousand, eight hundred eighty-one".