666655998 has 8 divisors (see below), whose sum is σ = 1333312008. Its totient is φ = 222218664.

The previous prime is 666655981. The next prime is 666656009. The reversal of 666655998 is 899556666.

It is a sphenic number, since it is the product of 3 distinct primes.

666655998 is an admirable number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55554661 + ... + 55554672.

It is an arithmetic number, because the mean of its divisors is an integer number (166664001).

Almost surely, 2^666655998 is an apocalyptic number.

666655998 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

666655998 is a wasteful number, since it uses less digits than its factorization.

666655998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111109338.

The product of its digits is 20995200, while the sum is 60.

The square root of 666655998 is about 25819.6823760479. The cubic root of 666655998 is about 873.5758047420.

The spelling of 666655998 in words is "six hundred sixty-six million, six hundred fifty-five thousand, nine hundred ninety-eight".