1998166 has 4 divisors (see below), whose sum is σ = 2997252. Its totient is φ = 999082.

The previous prime is 1998133. The next prime is 1998169. The reversal of 1998166 is 6618991.

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

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499540 + ... + 499543.

It is an arithmetic number, because the mean of its divisors is an integer number (749313).

2^1998166 is an apocalyptic number.

1998166 is a deficient number, since it is larger than the sum of its proper divisors (999086).

1998166 is an equidigital number, since it uses as much as digits as its factorization.

1998166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 999085.

The product of its digits is 23328, while the sum is 40.

The square root of 1998166 is about 1413.5649967370. The cubic root of 1998166 is about 125.9535816250.

The spelling of 1998166 in words is "one million, nine hundred ninety-eight thousand, one hundred sixty-six".