666881990 has 24 divisors (see below), whose sum is σ = 1206530640. Its totient is φ = 265392560.

The previous prime is 666881989. The next prime is 666881993. The reversal of 666881990 is 99188666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666881993) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1547075 + ... + 1547505.

It is an arithmetic number, because the mean of its divisors is an integer number (50272110).

Almost surely, 2^666881990 is an apocalyptic number.

666881990 is a deficient number, since it is larger than the sum of its proper divisors (539648650).

666881990 is an equidigital number, since it uses as much as digits as its factorization.

666881990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1228 (or 797 counting only the distinct ones).

The product of its (nonzero) digits is 1119744, while the sum is 53.

The square root of 666881990 is about 25824.0583565016. The cubic root of 666881990 is about 873.6745057412.

The spelling of 666881990 in words is "six hundred sixty-six million, eight hundred eighty-one thousand, nine hundred ninety".