311231221 has 16 divisors (see below), whose sum is σ = 361044864. Its totient is φ = 262785024.

The previous prime is 311231209. The next prime is 311231233. The reversal of 311231221 is 122132113.

It is an interprime number because it is at equal distance from previous prime (311231209) and next prime (311231233).

It is a cyclic number.

It is not a de Polignac number, because 311231221 - 2⁷ = 311231093 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 311231195 and 311231204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (311231201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 143481 + ... + 145633.

It is an arithmetic number, because the mean of its divisors is an integer number (22565304).

Almost surely, 2^311231221 is an apocalyptic number.

It is an amenable number.

311231221 is a deficient number, since it is larger than the sum of its proper divisors (49813643).

311231221 is a wasteful number, since it uses less digits than its factorization.

311231221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2460.

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

The square root of 311231221 is about 17641.7465405214. The cubic root of 311231221 is about 677.6847594575.

Adding to 311231221 its reverse (122132113), we get a palindrome (433363334).

The spelling of 311231221 in words is "three hundred eleven million, two hundred thirty-one thousand, two hundred twenty-one".