1791221 has 2 divisors, whose sum is σ = 1791222. Its totient is φ = 1791220.

The previous prime is 1791203. The next prime is 1791247. The reversal of 1791221 is 1221971.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 972196 + 819025 = 986^2 + 905^2 .

It is an emirp because it is prime and its reverse (1221971) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1791221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1791121) 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, 895610 + 895611.

It is an arithmetic number, because the mean of its divisors is an integer number (895611).

2^1791221 is an apocalyptic number.

It is an amenable number.

1791221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1791221 is an equidigital number, since it uses as much as digits as its factorization.

1791221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 252, while the sum is 23.

The square root of 1791221 is about 1338.3650473619. The cubic root of 1791221 is about 121.4459558567.

The spelling of 1791221 in words is "one million, seven hundred ninety-one thousand, two hundred twenty-one".