221636 has 12 divisors (see below), whose sum is σ = 394128. Its totient is φ = 109032.

The previous prime is 221623. The next prime is 221653. The reversal of 221636 is 636122.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221636.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 146 + ... + 681.

It is an arithmetic number, because the mean of its divisors is an integer number (32844).

2²²¹⁶³⁶ is an apocalyptic number.

It is an amenable number.

221636 is a deficient number, since it is larger than the sum of its proper divisors (172492).

221636 is a wasteful number, since it uses less digits than its factorization.

221636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 898 (or 896 counting only the distinct ones).

The product of its digits is 432, while the sum is 20.

The square root of 221636 is about 470.7823276207. The cubic root of 221636 is about 60.5173777005.

Adding to 221636 its reverse (636122), we get a palindrome (857758).

The spelling of 221636 in words is "two hundred twenty-one thousand, six hundred thirty-six".