221311213 has 4 divisors (see below), whose sum is σ = 222903520. Its totient is φ = 219718908.

The previous prime is 221311193. The next prime is 221311217. The reversal of 221311213 is 312113122.

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, and also an emirpimes, since its reverse is a distinct semiprime: 312113122 = 2 ⋅156056561.

It is a cyclic number.

It is not a de Polignac number, because 221311213 - 2²⁵ = 187756781 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221311217) 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, 795945 + ... + 796222.

It is an arithmetic number, because the mean of its divisors is an integer number (55725880).

Almost surely, 2^221311213 is an apocalyptic number.

It is an amenable number.

221311213 is a deficient number, since it is larger than the sum of its proper divisors (1592307).

221311213 is a wasteful number, since it uses less digits than its factorization.

221311213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1592306.

The product of its digits is 72, while the sum is 16.

The square root of 221311213 is about 14876.5322908264. The cubic root of 221311213 is about 604.8780238125.

Adding to 221311213 its reverse (312113122), we get a palindrome (533424335).

The spelling of 221311213 in words is "two hundred twenty-one million, three hundred eleven thousand, two hundred thirteen".