1685221 has 2 divisors, whose sum is σ = 1685222. Its totient is φ = 1685220.

The previous prime is 1685209. The next prime is 1685231. The reversal of 1685221 is 1225861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1276900 + 408321 = 1130^2 + 639^2 .

It is a cyclic number.

It is not a de Polignac number, because 1685221 - 2⁷ = 1685093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1685231) 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, 842610 + 842611.

It is an arithmetic number, because the mean of its divisors is an integer number (842611).

2^1685221 is an apocalyptic number.

It is an amenable number.

1685221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1685221 is an equidigital number, since it uses as much as digits as its factorization.

1685221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 960, while the sum is 25.

The square root of 1685221 is about 1298.1606218030. The cubic root of 1685221 is about 119.0014593894.

The spelling of 1685221 in words is "one million, six hundred eighty-five thousand, two hundred twenty-one".