1918391 has 2 divisors, whose sum is σ = 1918392. Its totient is φ = 1918390.

The previous prime is 1918363. The next prime is 1918417. The reversal of 1918391 is 1938191.

It is a strong prime.

It is an emirp because it is prime and its reverse (1938191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1918391 - 2⁶ = 1918327 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1918351) 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 as a sum of consecutive naturals, namely, 959195 + 959196.

It is an arithmetic number, because the mean of its divisors is an integer number (959196).

2^1918391 is an apocalyptic number.

1918391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1918391 is an equidigital number, since it uses as much as digits as its factorization.

1918391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1944, while the sum is 32.

The square root of 1918391 is about 1385.0599265014. The cubic root of 1918391 is about 124.2545715276.

The spelling of 1918391 in words is "one million, nine hundred eighteen thousand, three hundred ninety-one".