221501321 has 2 divisors, whose sum is σ = 221501322. Its totient is φ = 221501320.

The previous prime is 221501303. The next prime is 221501323. The reversal of 221501321 is 123105122.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 196140025 + 25361296 = 14005^2 + 5036^2 .

It is a cyclic number.

It is not a de Polignac number, because 221501321 - 2¹⁰ = 221500297 is a prime.

Together with 221501323, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221501321.

It is not a weakly prime, because it can be changed into another prime (221501323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110750660 + 110750661.

It is an arithmetic number, because the mean of its divisors is an integer number (110750661).

Almost surely, 2^221501321 is an apocalyptic number.

It is an amenable number.

221501321 is a deficient number, since it is larger than the sum of its proper divisors (1).

221501321 is an equidigital number, since it uses as much as digits as its factorization.

221501321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 221501321 is about 14882.9204459340. The cubic root of 221501321 is about 605.0511725038.

Adding to 221501321 its reverse (123105122), we get a palindrome (344606443).

The spelling of 221501321 in words is "two hundred twenty-one million, five hundred one thousand, three hundred twenty-one".