221636221 has 8 divisors (see below), whose sum is σ = 223804224. Its totient is φ = 219478560.

The previous prime is 221636213. The next prime is 221636231. The reversal of 221636221 is 122636122.

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

It is a cyclic number.

It is not a de Polignac number, because 221636221 - 2³ = 221636213 is a prime.

It is a super-2 number, since 2×221636221² = 98245228918321682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221636231) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44566 + ... + 49288.

It is an arithmetic number, because the mean of its divisors is an integer number (27975528).

Almost surely, 2^221636221 is an apocalyptic number.

It is an amenable number.

221636221 is a deficient number, since it is larger than the sum of its proper divisors (2168003).

221636221 is a wasteful number, since it uses less digits than its factorization.

221636221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5171.

The product of its digits is 1728, while the sum is 25.

The square root of 221636221 is about 14887.4517967314. The cubic root of 221636221 is about 605.1739781505.

Subtracting from 221636221 its reverse (122636122), we obtain a palindrome (99000099).

The spelling of 221636221 in words is "two hundred twenty-one million, six hundred thirty-six thousand, two hundred twenty-one".