221565 has 8 divisors (see below), whose sum is σ = 354528. Its totient is φ = 118160.

The previous prime is 221549. The next prime is 221567. The reversal of 221565 is 565122.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 221565 - 2⁴ = 221549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221567) 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 in 7 ways as a sum of consecutive naturals, for example, 7371 + ... + 7400.

It is an arithmetic number, because the mean of its divisors is an integer number (44316).

2²²¹⁵⁶⁵ is an apocalyptic number.

It is an amenable number.

221565 is a deficient number, since it is larger than the sum of its proper divisors (132963).

221565 is a wasteful number, since it uses less digits than its factorization.

221565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14779.

The product of its digits is 600, while the sum is 21.

The square root of 221565 is about 470.7069151818. The cubic root of 221565 is about 60.5109148624.

Adding to 221565 its reverse (565122), we get a palindrome (786687).

The spelling of 221565 in words is "two hundred twenty-one thousand, five hundred sixty-five".