668999998 has 4 divisors (see below), whose sum is σ = 1003500000. Its totient is φ = 334499998.

The previous prime is 668999987. The next prime is 668999999. The reversal of 668999998 is 899999866.

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

It is a self number, because there is not a number n which added to its sum of digits gives 668999998.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668999999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167249998 + ... + 167250001.

It is an arithmetic number, because the mean of its divisors is an integer number (250875000).

Almost surely, 2^668999998 is an apocalyptic number.

668999998 is a deficient number, since it is larger than the sum of its proper divisors (334500002).

668999998 is a wasteful number, since it uses less digits than its factorization.

668999998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334500001.

The product of its digits is 136048896, while the sum is 73.

The square root of 668999998 is about 25865.0342740929. The cubic root of 668999998 is about 874.5984543402.

The spelling of 668999998 in words is "six hundred sixty-eight million, nine hundred ninety-nine thousand, nine hundred ninety-eight".