221257 has 4 divisors (see below), whose sum is σ = 223636. Its totient is φ = 218880.

The previous prime is 221251. The next prime is 221261. The reversal of 221257 is 752122.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 116281 + 104976 = 341^2 + 324^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221257 is a prime.

It is a Duffinian number.

221257 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (221251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1044 + ... + 1237.

It is an arithmetic number, because the mean of its divisors is an integer number (55909).

2²²¹²⁵⁷ is an apocalyptic number.

It is an amenable number.

221257 is a deficient number, since it is larger than the sum of its proper divisors (2379).

221257 is an equidigital number, since it uses as much as digits as its factorization.

221257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2378.

The product of its digits is 280, while the sum is 19.

The square root of 221257 is about 470.3796339129. The cubic root of 221257 is about 60.4828628921.

Adding to 221257 its reverse (752122), we get a palindrome (973379).

The spelling of 221257 in words is "two hundred twenty-one thousand, two hundred fifty-seven".