1991293 has 2 divisors, whose sum is σ = 1991294. Its totient is φ = 1991292.

The previous prime is 1991281. The next prime is 1991351. The reversal of 1991293 is 3921991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1315609 + 675684 = 1147^2 + 822^2 .

It is an emirp because it is prime and its reverse (3921991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1991293 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1991243) 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, 995646 + 995647.

It is an arithmetic number, because the mean of its divisors is an integer number (995647).

2^1991293 is an apocalyptic number.

It is an amenable number.

1991293 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991293 is an equidigital number, since it uses as much as digits as its factorization.

1991293 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4374, while the sum is 34.

The square root of 1991293 is about 1411.1318152462. The cubic root of 1991293 is about 125.8090034780.

The spelling of 1991293 in words is "one million, nine hundred ninety-one thousand, two hundred ninety-three".