1991323 has 4 divisors (see below), whose sum is σ = 1995160. Its totient is φ = 1987488.

The previous prime is 1991293. The next prime is 1991351. The reversal of 1991323 is 3231991.

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

It is a cyclic number.

It is not a de Polignac number, because 1991323 - 2¹⁷ = 1860251 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1991291 and 1991300.

It is not an unprimeable number, because it can be changed into a prime (1991123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 990 + ... + 2227.

It is an arithmetic number, because the mean of its divisors is an integer number (498790).

2^1991323 is an apocalyptic number.

1991323 is a deficient number, since it is larger than the sum of its proper divisors (3837).

1991323 is an equidigital number, since it uses as much as digits as its factorization.

1991323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3836.

The product of its digits is 1458, while the sum is 28.

The square root of 1991323 is about 1411.1424449714. The cubic root of 1991323 is about 125.8096352704.

The spelling of 1991323 in words is "one million, nine hundred ninety-one thousand, three hundred twenty-three".