1646221 has 2 divisors, whose sum is σ = 1646222. Its totient is φ = 1646220.

The previous prime is 1646219. The next prime is 1646237. The reversal of 1646221 is 1226461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1022121 + 624100 = 1011^2 + 790^2 .

It is an emirp because it is prime and its reverse (1226461) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1646221 - 2¹ = 1646219 is a prime.

Together with 1646219, it forms a pair of twin primes.

1646221 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1646192 and 1646201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1646261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 823110 + 823111.

It is an arithmetic number, because the mean of its divisors is an integer number (823111).

2^1646221 is an apocalyptic number.

It is an amenable number.

1646221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1646221 is an equidigital number, since it uses as much as digits as its factorization.

1646221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 576, while the sum is 22.

The square root of 1646221 is about 1283.0514409017. The cubic root of 1646221 is about 118.0762936661.

The spelling of 1646221 in words is "one million, six hundred forty-six thousand, two hundred twenty-one".