2181800 has 24 divisors (see below), whose sum is σ = 5073150. Its totient is φ = 872640.

The previous prime is 2181737. The next prime is 2181833. The reversal of 2181800 is 81812.

It can be written as a sum of positive squares in 3 ways, for example, as 1331716 + 850084 = 1154^2 + 922^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5255 + ... + 5654.

2^2181800 is an apocalyptic number.

2181800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2181800 is an abundant number, since it is smaller than the sum of its proper divisors (2891350).

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

2181800 is a wasteful number, since it uses less digits than its factorization.

2181800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10925 (or 10916 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 20.

The square root of 2181800 is about 1477.0917371646. The cubic root of 2181800 is about 129.6995031712.

The spelling of 2181800 in words is "two million, one hundred eighty-one thousand, eight hundred".