1991297 has 12 divisors (see below), whose sum is σ = 2502528. Its totient is φ = 1551000.

The previous prime is 1991293. The next prime is 1991351. The reversal of 1991297 is 7921991.

It is not a de Polignac number, because 1991297 - 2² = 1991293 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1991297.

It is not an unprimeable number, because it can be changed into a prime (1991293) 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, 329 + ... + 2022.

It is an arithmetic number, because the mean of its divisors is an integer number (208544).

2^1991297 is an apocalyptic number.

It is an amenable number.

1991297 is a deficient number, since it is larger than the sum of its proper divisors (511231).

1991297 is a wasteful number, since it uses less digits than its factorization.

1991297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2380 (or 2369 counting only the distinct ones).

The product of its digits is 10206, while the sum is 38.

The square root of 1991297 is about 1411.1332325475. The cubic root of 1991297 is about 125.8090877174.

The spelling of 1991297 in words is "one million, nine hundred ninety-one thousand, two hundred ninety-seven".