2181900 has 72 divisors (see below), whose sum is σ = 7221760. Its totient is φ = 498240.

The previous prime is 2181889. The next prime is 2181919. The reversal of 2181900 is 91812.

It is a super-2 number, since 2×2181900² = 9521375220000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1581 + ... + 2619.

2^2181900 is an apocalyptic number.

2181900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2181900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3610880).

2181900 is an abundant number, since it is smaller than the sum of its proper divisors (5039860).

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

2181900 is a wasteful number, since it uses less digits than its factorization.

2181900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1063 (or 1056 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 2181900 is about 1477.1255870778. The cubic root of 2181900 is about 129.7014846776.

It can be divided in two parts, 2181 and 900, that added together give a triangular number (3081 = T₇₈).

The spelling of 2181900 in words is "two million, one hundred eighty-one thousand, nine hundred".