1326991 has 4 divisors (see below), whose sum is σ = 1329912. Its totient is φ = 1324072.

The previous prime is 1326989. The next prime is 1327009. The reversal of 1326991 is 1996231.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1996231 = 47 ⋅42473.

It is a cyclic number.

It is not a de Polignac number, because 1326991 - 2¹ = 1326989 is a prime.

It is a super-2 number, since 2×1326991² = 3521810228162, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1326971) 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 3 ways as a sum of consecutive naturals, for example, 616 + ... + 1741.

It is an arithmetic number, because the mean of its divisors is an integer number (332478).

2^1326991 is an apocalyptic number.

1326991 is a deficient number, since it is larger than the sum of its proper divisors (2921).

1326991 is an equidigital number, since it uses as much as digits as its factorization.

1326991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2920.

The product of its digits is 2916, while the sum is 31.

The square root of 1326991 is about 1151.9509538170. The cubic root of 1326991 is about 109.8894481594.

The spelling of 1326991 in words is "one million, three hundred twenty-six thousand, nine hundred ninety-one".