1801861 has 4 divisors (see below), whose sum is σ = 1808512. Its totient is φ = 1795212.

The previous prime is 1801853. The next prime is 1801867. The reversal of 1801861 is 1681081.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1681081 = 1129 ⋅1489.

It is a cyclic number.

It is not a de Polignac number, because 1801861 - 2³ = 1801853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1801867) 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, 2901 + ... + 3466.

It is an arithmetic number, because the mean of its divisors is an integer number (452128).

2^1801861 is an apocalyptic number.

It is an amenable number.

1801861 is a deficient number, since it is larger than the sum of its proper divisors (6651).

1801861 is an equidigital number, since it uses as much as digits as its factorization.

1801861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6650.

The product of its (nonzero) digits is 384, while the sum is 25.

The square root of 1801861 is about 1342.3341610791. The cubic root of 1801861 is about 121.6859476126.

It can be divided in two parts, 1801 and 861, that added together give a palindrome (2662).

The spelling of 1801861 in words is "one million, eight hundred one thousand, eight hundred sixty-one".