1920221 has 2 divisors, whose sum is σ = 1920222. Its totient is φ = 1920220.

The previous prime is 1920211. The next prime is 1920223. The reversal of 1920221 is 1220291.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1768900 + 151321 = 1330^2 + 389^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1920221 is a prime.

Together with 1920223, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1920221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1920223) 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, 960110 + 960111.

It is an arithmetic number, because the mean of its divisors is an integer number (960111).

2^1920221 is an apocalyptic number.

It is an amenable number.

1920221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1920221 is an equidigital number, since it uses as much as digits as its factorization.

1920221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 1920221 is about 1385.7203902664. The cubic root of 1920221 is about 124.2940687940.

The spelling of 1920221 in words is "one million, nine hundred twenty thousand, two hundred twenty-one".