1840 has 20 divisors (see below), whose sum is σ = 4464. Its totient is φ = 704.

The previous prime is 1831. The next prime is 1847. The reversal of 1840 is 481.

It is a tau number, because it is divible by the number of its divisors (20).

It is a nialpdrome in base 16.

It is a zygodrome in base 2.

It is a self number, because there is not a number n which added to its sum of digits gives 1840.

It is not an unprimeable number, because it can be changed into a prime (1847) by changing a digit.

1840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 69 + ... + 91.

1840 is a gapful number since it is divisible by the number (10) 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 1840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2232).

1840 is an abundant number, since it is smaller than the sum of its proper divisors (2624).

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

1840 is a wasteful number, since it uses less digits than its factorization.

1840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36 (or 30 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 1840 is about 42.8952211791. The cubic root of 1840 is about 12.2538513505.

It can be divided in two parts, 1 and 840, that added together give a square (841 = 29²).

The spelling of 1840 in words is "one thousand, eight hundred forty".