666777658 has 4 divisors (see below), whose sum is σ = 1000166490. Its totient is φ = 333388828.

The previous prime is 666777653. The next prime is 666777677. The reversal of 666777658 is 856777666.

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., 588402049 + 78375609 = 24257^2 + 8853^2 .

It is not an unprimeable number, because it can be changed into a prime (666777653) by changing a digit.

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 as a sum of consecutive naturals, namely, 166694413 + ... + 166694416.

Almost surely, 2^666777658 is an apocalyptic number.

666777658 is a deficient number, since it is larger than the sum of its proper divisors (333388832).

666777658 is a wasteful number, since it uses less digits than its factorization.

666777658 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333388831.

The product of its digits is 17781120, while the sum is 58.

The square root of 666777658 is about 25822.0382231922. The cubic root of 666777658 is about 873.6289419764.

The spelling of 666777658 in words is "six hundred sixty-six million, seven hundred seventy-seven thousand, six hundred fifty-eight".