1991854 has 4 divisors (see below), whose sum is σ = 2987784. Its totient is φ = 995926.

The previous prime is 1991849. The next prime is 1991861. The reversal of 1991854 is 4581991.

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

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 497962 + ... + 497965.

It is an arithmetic number, because the mean of its divisors is an integer number (746946).

2^1991854 is an apocalyptic number.

1991854 is a deficient number, since it is larger than the sum of its proper divisors (995930).

1991854 is an equidigital number, since it uses as much as digits as its factorization.

1991854 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 995929.

The product of its digits is 12960, while the sum is 37.

The square root of 1991854 is about 1411.3305778591. The cubic root of 1991854 is about 125.8208169453.

The spelling of 1991854 in words is "one million, nine hundred ninety-one thousand, eight hundred fifty-four".