1320391 has 2 divisors, whose sum is σ = 1320392. Its totient is φ = 1320390.

The previous prime is 1320379. The next prime is 1320409. The reversal of 1320391 is 1930231.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1320391 - 2¹⁵ = 1287623 is a prime.

It is a Chen prime.

1320391 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1320301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660195 + 660196.

It is an arithmetic number, because the mean of its divisors is an integer number (660196).

2^1320391 is an apocalyptic number.

1320391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1320391 is an equidigital number, since it uses as much as digits as its factorization.

1320391 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 162, while the sum is 19.

The square root of 1320391 is about 1149.0826776172. The cubic root of 1320391 is about 109.7069610873.

It can be divided in two parts, 1320 and 391, that added together give a triangular number (1711 = T₅₈).

The spelling of 1320391 in words is "one million, three hundred twenty thousand, three hundred ninety-one".