1998866 has 4 divisors (see below), whose sum is σ = 2998302. Its totient is φ = 999432.

The previous prime is 1998839. The next prime is 1998881. The reversal of 1998866 is 6688991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6688991 = 131 ⋅51061.

It can be written as a sum of positive squares in only one way, i.e., 1890625 + 108241 = 1375^2 + 329^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 1998866.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499715 + ... + 499718.

2^1998866 is an apocalyptic number.

1998866 is a deficient number, since it is larger than the sum of its proper divisors (999436).

1998866 is an equidigital number, since it uses as much as digits as its factorization.

1998866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 999435.

The product of its digits is 186624, while the sum is 47.

The square root of 1998866 is about 1413.8125759803. The cubic root of 1998866 is about 125.9682879797.

The spelling of 1998866 in words is "one million, nine hundred ninety-eight thousand, eight hundred sixty-six".