1661843 has 4 divisors (see below), whose sum is σ = 1665168. Its totient is φ = 1658520.

The previous prime is 1661839. The next prime is 1661851. The reversal of 1661843 is 3481661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3481661 = 1087 ⋅3203.

It is a cyclic number.

It is not a de Polignac number, because 1661843 - 2² = 1661839 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661813) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 743 + ... + 1968.

It is an arithmetic number, because the mean of its divisors is an integer number (416292).

2^1661843 is an apocalyptic number.

1661843 is a deficient number, since it is larger than the sum of its proper divisors (3325).

1661843 is an equidigital number, since it uses as much as digits as its factorization.

1661843 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3324.

The product of its digits is 3456, while the sum is 29.

The square root of 1661843 is about 1289.1248969747. The cubic root of 1661843 is about 118.4486178395.

It can be divided in two parts, 16618 and 43, that added together give a palindrome (16661).

The spelling of 1661843 in words is "one million, six hundred sixty-one thousand, eight hundred forty-three".