1661800 has 48 divisors (see below), whose sum is σ = 4419360. Its totient is φ = 569280.

The previous prime is 1661789. The next prime is 1661813. The reversal of 1661800 is 81661.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 807 + ... + 1993.

It is an arithmetic number, because the mean of its divisors is an integer number (92070).

2^1661800 is an apocalyptic number.

1661800 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 1661800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2209680).

1661800 is an abundant number, since it is smaller than the sum of its proper divisors (2757560).

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

1661800 is a wasteful number, since it uses less digits than its factorization.

1661800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1210 (or 1201 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 1661800 is about 1289.1082188862. The cubic root of 1661800 is about 118.4475962158.

It can be divided in two parts, 16 and 61800, that added together give a palindrome (61816).

The spelling of 1661800 in words is "one million, six hundred sixty-one thousand, eight hundred".