2181998 has 32 divisors (see below), whose sum is σ = 4247040. Its totient is φ = 816480.

The previous prime is 2181973. The next prime is 2182007. The reversal of 2181998 is 8991812.

2181998 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×2181998² = 9522230544008, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (38).

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3143 + ... + 3773.

It is an arithmetic number, because the mean of its divisors is an integer number (132720).

2^2181998 is an apocalyptic number.

2181998 is a deficient number, since it is larger than the sum of its proper divisors (2065042).

2181998 is a wasteful number, since it uses less digits than its factorization.

2181998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 672.

The product of its digits is 10368, while the sum is 38.

The square root of 2181998 is about 1477.1587592402. The cubic root of 2181998 is about 129.7034264952.

The spelling of 2181998 in words is "two million, one hundred eighty-one thousand, nine hundred ninety-eight".