1990855 has 4 divisors (see below), whose sum is σ = 2389032. Its totient is φ = 1592680.

The previous prime is 1990831. The next prime is 1990867. The reversal of 1990855 is 5580991.

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

It is not a de Polignac number, because 1990855 - 2⁵ = 1990823 is a prime.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 199081 + ... + 199090.

It is an arithmetic number, because the mean of its divisors is an integer number (597258).

2^1990855 is an apocalyptic number.

1990855 is a deficient number, since it is larger than the sum of its proper divisors (398177).

1990855 is an equidigital number, since it uses as much as digits as its factorization.

1990855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398176.

The product of its (nonzero) digits is 16200, while the sum is 37.

The square root of 1990855 is about 1410.9766121378. The cubic root of 1990855 is about 125.7997785868.

The spelling of 1990855 in words is "one million, nine hundred ninety thousand, eight hundred fifty-five".