221457 has 4 divisors (see below), whose sum is σ = 295280. Its totient is φ = 147636.

The previous prime is 221453. The next prime is 221461. The reversal of 221457 is 754122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (221453) and next prime (221461).

It is not a de Polignac number, because 221457 - 2² = 221453 is a prime.

It is a D-number.

It is a Duffinian number.

221457 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (221453) 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, 36907 + ... + 36912.

It is an arithmetic number, because the mean of its divisors is an integer number (73820).

2²²¹⁴⁵⁷ is an apocalyptic number.

It is an amenable number.

221457 is a deficient number, since it is larger than the sum of its proper divisors (73823).

221457 is an equidigital number, since it uses as much as digits as its factorization.

221457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73822.

The product of its digits is 560, while the sum is 21.

The square root of 221457 is about 470.5921801305. The cubic root of 221457 is about 60.5010814186.

Adding to 221457 its reverse (754122), we get a palindrome (975579).

The spelling of 221457 in words is "two hundred twenty-one thousand, four hundred fifty-seven".