1691321 has 2 divisors, whose sum is σ = 1691322. Its totient is φ = 1691320.

The previous prime is 1691303. The next prime is 1691359. The reversal of 1691321 is 1231961.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1254400 + 436921 = 1120^2 + 661^2 .

It is an emirp because it is prime and its reverse (1231961) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1691321 - 2⁶ = 1691257 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1691621) 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, 845660 + 845661.

It is an arithmetic number, because the mean of its divisors is an integer number (845661).

2^1691321 is an apocalyptic number.

It is an amenable number.

1691321 is a deficient number, since it is larger than the sum of its proper divisors (1).

1691321 is an equidigital number, since it uses as much as digits as its factorization.

1691321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 324, while the sum is 23.

The square root of 1691321 is about 1300.5079776764. The cubic root of 1691321 is about 119.1448698187.

The spelling of 1691321 in words is "one million, six hundred ninety-one thousand, three hundred twenty-one".