1991373 has 12 divisors (see below), whose sum is σ = 2725920. Its totient is φ = 1293096.

The previous prime is 1991359. The next prime is 1991387. The reversal of 1991373 is 3731991.

It is an interprime number because it is at equal distance from previous prime (1991359) and next prime (1991387).

It is not a de Polignac number, because 1991373 - 2⁴ = 1991357 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991573) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5368 + ... + 5726.

It is an arithmetic number, because the mean of its divisors is an integer number (227160).

2^1991373 is an apocalyptic number.

It is an amenable number.

1991373 is a deficient number, since it is larger than the sum of its proper divisors (734547).

1991373 is an equidigital number, since it uses as much as digits as its factorization.

1991373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 448 (or 405 counting only the distinct ones).

The product of its digits is 5103, while the sum is 33.

The square root of 1991373 is about 1411.1601610023. The cubic root of 1991373 is about 125.8106882436.

The spelling of 1991373 in words is "one million, nine hundred ninety-one thousand, three hundred seventy-three".