1816861 has 2 divisors, whose sum is σ = 1816862. Its totient is φ = 1816860.

The previous prime is 1816853. The next prime is 1816901. The reversal of 1816861 is 1686181.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1768900 + 47961 = 1330^2 + 219^2 .

It is a cyclic number.

It is not a de Polignac number, because 1816861 - 2³ = 1816853 is a prime.

1816861 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1816831) 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 as a sum of consecutive naturals, namely, 908430 + 908431.

It is an arithmetic number, because the mean of its divisors is an integer number (908431).

2^1816861 is an apocalyptic number.

It is an amenable number.

1816861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1816861 is an equidigital number, since it uses as much as digits as its factorization.

1816861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2304, while the sum is 31.

The square root of 1816861 is about 1347.9098634553. The cubic root of 1816861 is about 122.0226823364.

The spelling of 1816861 in words is "one million, eight hundred sixteen thousand, eight hundred sixty-one".