57221 has 2 divisors, whose sum is σ = 57222. Its totient is φ = 57220.

The previous prime is 57203. The next prime is 57223. The reversal of 57221 is 12275.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57121 + 100 = 239^2 + 10^2 .

It is a cyclic number.

It is not a de Polignac number, because 57221 - 2¹⁰ = 56197 is a prime.

Together with 57223, 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 57221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (57223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28610 + 28611.

It is an arithmetic number, because the mean of its divisors is an integer number (28611).

2⁵⁷²²¹ is an apocalyptic number.

It is an amenable number.

57221 is a deficient number, since it is larger than the sum of its proper divisors (1).

57221 is an equidigital number, since it uses as much as digits as its factorization.

57221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 140, while the sum is 17.

The square root of 57221 is about 239.2091135388. The cubic root of 57221 is about 38.5346851083.

Adding to 57221 its reverse (12275), we get a palindrome (69496).

The spelling of 57221 in words is "fifty-seven thousand, two hundred twenty-one".