667998 has 48 divisors (see below), whose sum is σ = 1600560. Its totient is φ = 200448.

The previous prime is 667991. The next prime is 667999. The reversal of 667998 is 899766.

667998 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667991) by changing a digit.

667998 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11293 + ... + 11351.

It is an arithmetic number, because the mean of its divisors is an integer number (33345).

2⁶⁶⁷⁹⁹⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 667998, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (800280).

667998 is an abundant number, since it is smaller than the sum of its proper divisors (932562).

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

667998 is a wasteful number, since it uses less digits than its factorization.

667998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121 (or 118 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 667998 is about 817.3114461452. The cubic root of 667998 is about 87.4161591467.

The spelling of 667998 in words is "six hundred sixty-seven thousand, nine hundred ninety-eight".