1981800 has 96 divisors (see below), whose sum is σ = 6844800. Its totient is φ = 527040.

The previous prime is 1981787. The next prime is 1981813. The reversal of 1981800 is 81891.

It is an interprime number because it is at equal distance from previous prime (1981787) and next prime (1981813).

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 5217 + ... + 5583.

It is an arithmetic number, because the mean of its divisors is an integer number (71300).

2^1981800 is an apocalyptic number.

1981800 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 1981800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3422400).

1981800 is an abundant number, since it is smaller than the sum of its proper divisors (4863000).

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

1981800 is a wasteful number, since it uses less digits than its factorization.

1981800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 392 (or 377 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 27.

The square root of 1981800 is about 1407.7641847980. The cubic root of 1981800 is about 125.6087637738.

The spelling of 1981800 in words is "one million, nine hundred eighty-one thousand, eight hundred".