666991290 has 32 divisors (see below), whose sum is σ = 1829462400. Its totient is φ = 152455104.

The previous prime is 666991289. The next prime is 666991301. The reversal of 666991290 is 92199666.

It is a happy number.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1587865 + ... + 1588284.

It is an arithmetic number, because the mean of its divisors is an integer number (57170700).

Almost surely, 2^666991290 is an apocalyptic number.

666991290 is an abundant number, since it is smaller than the sum of its proper divisors (1162471110).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

666991290 is a wasteful number, since it uses less digits than its factorization.

666991290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3176166.

The product of its (nonzero) digits is 314928, while the sum is 48.

The square root of 666991290 is about 25826.1745134660. The cubic root of 666991290 is about 873.7222340292.

The spelling of 666991290 in words is "six hundred sixty-six million, nine hundred ninety-one thousand, two hundred ninety".