221315321 has 4 divisors (see below), whose sum is σ = 223802100. Its totient is φ = 218828544.

The previous prime is 221315317. The next prime is 221315323. The reversal of 221315321 is 123513122.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 73960000 + 147355321 = 8600^2 + 12139^2 .

It is a cyclic number.

It is not a de Polignac number, because 221315321 - 2² = 221315317 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221315293 and 221315302.

It is not an unprimeable number, because it can be changed into a prime (221315323) 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, 1243256 + ... + 1243433.

It is an arithmetic number, because the mean of its divisors is an integer number (55950525).

Almost surely, 2^221315321 is an apocalyptic number.

It is an amenable number.

221315321 is a deficient number, since it is larger than the sum of its proper divisors (2486779).

221315321 is an equidigital number, since it uses as much as digits as its factorization.

221315321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2486778.

The product of its digits is 360, while the sum is 20.

The square root of 221315321 is about 14876.6703599966. The cubic root of 221315321 is about 604.8817663907.

Adding to 221315321 its reverse (123513122), we get a palindrome (344828443).

The spelling of 221315321 in words is "two hundred twenty-one million, three hundred fifteen thousand, three hundred twenty-one".