31122221 has 4 divisors (see below), whose sum is σ = 33516252. Its totient is φ = 28728192.

The previous prime is 31122173. The next prime is 31122229. The reversal of 31122221 is 12222113.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12222113 = 881 ⋅13873.

It can be written as a sum of positive squares in 2 ways, for example, as 6817321 + 24304900 = 2611^2 + 4930^2 .

It is a cyclic number.

It is not a de Polignac number, because 31122221 - 2¹⁰ = 31121197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31122196 and 31122205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31122229) 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, 1196996 + ... + 1197021.

It is an arithmetic number, because the mean of its divisors is an integer number (8379063).

Almost surely, 2^31122221 is an apocalyptic number.

It is an amenable number.

31122221 is a deficient number, since it is larger than the sum of its proper divisors (2394031).

31122221 is a wasteful number, since it uses less digits than its factorization.

31122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2394030.

The product of its digits is 48, while the sum is 14.

The square root of 31122221 is about 5578.7293356104. The cubic root of 31122221 is about 314.5503654627.

Adding to 31122221 its reverse (12222113), we get a palindrome (43344334).

The spelling of 31122221 in words is "thirty-one million, one hundred twenty-two thousand, two hundred twenty-one".