666986986 has 4 divisors (see below), whose sum is σ = 1000480482. Its totient is φ = 333493492.

The previous prime is 666986977. The next prime is 666986987. The reversal of 666986986 is 689689666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 653773761 + 13213225 = 25569^2 + 3635^2 .

It is not an unprimeable number, because it can be changed into a prime (666986987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166746745 + ... + 166746748.

Almost surely, 2^666986986 is an apocalyptic number.

666986986 is a deficient number, since it is larger than the sum of its proper divisors (333493496).

666986986 is a wasteful number, since it uses less digits than its factorization.

666986986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333493495.

The product of its digits is 40310784, while the sum is 64.

The square root of 666986986 is about 25826.0911870147. The cubic root of 666986986 is about 873.7203546900.

The spelling of 666986986 in words is "six hundred sixty-six million, nine hundred eighty-six thousand, nine hundred eighty-six".