1861855 has 4 divisors (see below), whose sum is σ = 2234232. Its totient is φ = 1489480.

The previous prime is 1861831. The next prime is 1861859. The reversal of 1861855 is 5581681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5581681 = 7 ⋅797383.

It is a de Polignac number, because none of the positive numbers 2^k-1861855 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1861855.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1861859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 186181 + ... + 186190.

It is an arithmetic number, because the mean of its divisors is an integer number (558558).

2^1861855 is an apocalyptic number.

1861855 is a deficient number, since it is larger than the sum of its proper divisors (372377).

1861855 is an equidigital number, since it uses as much as digits as its factorization.

1861855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 372376.

The product of its digits is 9600, while the sum is 34.

The square root of 1861855 is about 1364.4980762170. The cubic root of 1861855 is about 123.0217644964.

The spelling of 1861855 in words is "one million, eight hundred sixty-one thousand, eight hundred fifty-five".