2181840 has 40 divisors (see below), whose sum is σ = 6764448. Its totient is φ = 581760.

The previous prime is 2181833. The next prime is 2181857. The reversal of 2181840 is 481812.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 2181840.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4306 + ... + 4785.

2^2181840 is an apocalyptic number.

2181840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2181840 is an abundant number, since it is smaller than the sum of its proper divisors (4582608).

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

2181840 is a wasteful number, since it uses less digits than its factorization.

2181840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9107 (or 9101 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 2181840 is about 1477.1052772230. The cubic root of 2181840 is about 129.7002957810.

The spelling of 2181840 in words is "two million, one hundred eighty-one thousand, eight hundred forty".