1317991 has 4 divisors (see below), whose sum is σ = 1328184. Its totient is φ = 1307800.

The previous prime is 1317989. The next prime is 1318003. The reversal of 1317991 is 1997131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1997131 = 283 ⋅7057.

It is a cyclic number.

It is not a de Polignac number, because 1317991 - 2¹ = 1317989 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 (1317941) 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, 4900 + ... + 5161.

It is an arithmetic number, because the mean of its divisors is an integer number (332046).

2^1317991 is an apocalyptic number.

1317991 is a deficient number, since it is larger than the sum of its proper divisors (10193).

1317991 is a wasteful number, since it uses less digits than its factorization.

1317991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10192.

The product of its digits is 1701, while the sum is 31.

The square root of 1317991 is about 1148.0378913607. The cubic root of 1317991 is about 109.6404513957.

The spelling of 1317991 in words is "one million, three hundred seventeen thousand, nine hundred ninety-one".