221221136 has 80 divisors (see below), whose sum is σ = 470505600. Its totient is φ = 100362240.

The previous prime is 221221127. The next prime is 221221213. The reversal of 221221136 is 631122122.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1111565 + ... + 1111763.

It is an arithmetic number, because the mean of its divisors is an integer number (5881320).

Almost surely, 2^221221136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221221136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (235252800).

221221136 is an abundant number, since it is smaller than the sum of its proper divisors (249284464).

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

221221136 is a wasteful number, since it uses less digits than its factorization.

221221136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 352 (or 346 counting only the distinct ones).

The product of its digits is 288, while the sum is 20.

The square root of 221221136 is about 14873.5044962510. The cubic root of 221221136 is about 604.7959478513.

Adding to 221221136 its reverse (631122122), we get a palindrome (852343258).

The spelling of 221221136 in words is "two hundred twenty-one million, two hundred twenty-one thousand, one hundred thirty-six".