221736 has 16 divisors (see below), whose sum is σ = 554400. Its totient is φ = 73904.

The previous prime is 221729. The next prime is 221737. The reversal of 221736 is 637122.

It is a happy number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221736.

It is not an unprimeable number, because it can be changed into a prime (221737) by changing a digit.

221736 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 4596 + ... + 4643.

It is an arithmetic number, because the mean of its divisors is an integer number (34650).

2²²¹⁷³⁶ is an apocalyptic number.

It is an amenable number.

221736 is an abundant number, since it is smaller than the sum of its proper divisors (332664).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221736 is a wasteful number, since it uses less digits than its factorization.

221736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9248 (or 9244 counting only the distinct ones).

The product of its digits is 504, while the sum is 21.

The square root of 221736 is about 470.8885218393. Note that the first 3 decimals coincide. The cubic root of 221736 is about 60.5264779487.

Adding to 221736 its reverse (637122), we get a palindrome (858858).

The spelling of 221736 in words is "two hundred twenty-one thousand, seven hundred thirty-six".