1861643 has 16 divisors (see below), whose sum is σ = 2297856. Its totient is φ = 1473120.

The previous prime is 1861637. The next prime is 1861649. The reversal of 1861643 is 3461681.

It is an interprime number because it is at equal distance from previous prime (1861637) and next prime (1861649).

It is not a de Polignac number, because 1861643 - 2⁶ = 1861579 is a prime.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1861649) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4805 + ... + 5177.

It is an arithmetic number, because the mean of its divisors is an integer number (143616).

2^1861643 is an apocalyptic number.

1861643 is a deficient number, since it is larger than the sum of its proper divisors (436213).

1861643 is a wasteful number, since it uses less digits than its factorization.

1861643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434.

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

The square root of 1861643 is about 1364.4203897626. The cubic root of 1861643 is about 123.0170950307.

The spelling of 1861643 in words is "one million, eight hundred sixty-one thousand, six hundred forty-three".