221501221 has 4 divisors (see below), whose sum is σ = 233159200. Its totient is φ = 209843244.

The previous prime is 221501207. The next prime is 221501237. The reversal of 221501221 is 122105122.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221501221 - 2⁹ = 221500709 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221501195 and 221501204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221501321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5828961 + ... + 5828998.

It is an arithmetic number, because the mean of its divisors is an integer number (58289800).

Almost surely, 2^221501221 is an apocalyptic number.

It is an amenable number.

221501221 is a deficient number, since it is larger than the sum of its proper divisors (11657979).

221501221 is a wasteful number, since it uses less digits than its factorization.

221501221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11657978.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 221501221 is about 14882.9170863779. The cubic root of 221501221 is about 605.0510814507.

Adding to 221501221 its reverse (122105122), we get a palindrome (343606343).

The spelling of 221501221 in words is "two hundred twenty-one million, five hundred one thousand, two hundred twenty-one".