668138798 has 8 divisors (see below), whose sum is σ = 1003534392. Its totient is φ = 333627336.

The previous prime is 668138789. The next prime is 668138803. The reversal of 668138798 is 897831866.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 219140 + ... + 222167.

It is an arithmetic number, because the mean of its divisors is an integer number (125441799).

Almost surely, 2^668138798 is an apocalyptic number.

668138798 is a deficient number, since it is larger than the sum of its proper divisors (335395594).

668138798 is a wasteful number, since it uses less digits than its factorization.

668138798 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 442066.

The product of its digits is 3483648, while the sum is 56.

The square root of 668138798 is about 25848.3809551005. The cubic root of 668138798 is about 874.2230046038.

The spelling of 668138798 in words is "six hundred sixty-eight million, one hundred thirty-eight thousand, seven hundred ninety-eight".