311221 has 4 divisors (see below), whose sum is σ = 313600. Its totient is φ = 308844.

The previous prime is 311203. The next prime is 311237. The reversal of 311221 is 122113.

311221 = T₄₅₄ + T₄₅₅ + T₄₅₆.

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: 122113 = 19 ⋅6427.

It is a cyclic number.

It is not a de Polignac number, because 311221 - 2⁵ = 311189 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 311198 and 311207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (311291) 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 3 ways as a sum of consecutive naturals, for example, 981 + ... + 1258.

It is an arithmetic number, because the mean of its divisors is an integer number (78400).

2³¹¹²²¹ is an apocalyptic number.

311221 is the 456-th centered triangular number.

It is an amenable number.

311221 is a deficient number, since it is larger than the sum of its proper divisors (2379).

311221 is a wasteful number, since it uses less digits than its factorization.

311221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2378.

The product of its digits is 12, while the sum is 10.

The square root of 311221 is about 557.8718490836. The cubic root of 311221 is about 67.7677340866.

Adding to 311221 its reverse (122113), we get a palindrome (433334).

The spelling of 311221 in words is "three hundred eleven thousand, two hundred twenty-one", and thus it is an iban number.