1991983 has 8 divisors (see below), whose sum is σ = 2285568. Its totient is φ = 1700664.

The previous prime is 1991963. The next prime is 1991989. The reversal of 1991983 is 3891991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-1991983 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 (1991989) 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 7 ways as a sum of consecutive naturals, for example, 2310 + ... + 3052.

It is an arithmetic number, because the mean of its divisors is an integer number (285696).

2^1991983 is an apocalyptic number.

1991983 is a deficient number, since it is larger than the sum of its proper divisors (293585).

1991983 is an equidigital number, since it uses as much as digits as its factorization.

1991983 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1133.

The product of its digits is 17496, while the sum is 40.

The square root of 1991983 is about 1411.3762786727. The cubic root of 1991983 is about 125.8235330974.

It can be divided in two parts, 19919 and 83, that added together give a palindrome (20002).

The spelling of 1991983 in words is "one million, nine hundred ninety-one thousand, nine hundred eighty-three".