221623 has 2 divisors, whose sum is σ = 221624. Its totient is φ = 221622.

The previous prime is 221621. The next prime is 221653. The reversal of 221623 is 326122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221623 - 2¹ = 221621 is a prime.

Together with 221621, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 221597 and 221606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221621) 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 as a sum of consecutive naturals, namely, 110811 + 110812.

It is an arithmetic number, because the mean of its divisors is an integer number (110812).

2²²¹⁶²³ is an apocalyptic number.

221623 is a deficient number, since it is larger than the sum of its proper divisors (1).

221623 is an equidigital number, since it uses as much as digits as its factorization.

221623 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 144, while the sum is 16.

The square root of 221623 is about 470.7685206128. The cubic root of 221623 is about 60.5161944672.

Adding to 221623 its reverse (326122), we get a palindrome (547745).

The spelling of 221623 in words is "two hundred twenty-one thousand, six hundred twenty-three".