1820855 has 4 divisors (see below), whose sum is σ = 2185032. Its totient is φ = 1456680.

The previous prime is 1820843. The next prime is 1820857. The reversal of 1820855 is 5580281.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1820855 - 2¹⁶ = 1755319 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 (1820857) 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, 182081 + ... + 182090.

It is an arithmetic number, because the mean of its divisors is an integer number (546258).

2^1820855 is an apocalyptic number.

1820855 is a deficient number, since it is larger than the sum of its proper divisors (364177).

1820855 is an equidigital number, since it uses as much as digits as its factorization.

1820855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364176.

The product of its (nonzero) digits is 3200, while the sum is 29.

The square root of 1820855 is about 1349.3906031983. The cubic root of 1820855 is about 122.1120309270.

The spelling of 1820855 in words is "one million, eight hundred twenty thousand, eight hundred fifty-five".