31321 has 2 divisors, whose sum is σ = 31322. Its totient is φ = 31320.

The previous prime is 31319. The next prime is 31327. The reversal of 31321 is 12313.

31321 = T₁₄₃ + T₁₄₄ + T₁₄₅.

31321 is nontrivially palindromic in base 12.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27225 + 4096 = 165^2 + 64^2 .

It is a cyclic number.

It is not a de Polignac number, because 31321 - 2¹ = 31319 is a prime.

Together with 31319, it forms a pair of twin primes.

31321 is an undulating number in base 12.

It is a plaindrome in base 13.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 31298 and 31307.

It is not a weakly prime, because it can be changed into another prime (31327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15660 + 15661.

It is an arithmetic number, because the mean of its divisors is an integer number (15661).

2³¹³²¹ is an apocalyptic number.

31321 is the 145-th centered triangular number.

It is an amenable number.

31321 is a deficient number, since it is larger than the sum of its proper divisors (1).

31321 is an equidigital number, since it uses as much as digits as its factorization.

31321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18, while the sum is 10.

The square root of 31321 is about 176.9773996871. The cubic root of 31321 is about 31.5218627095.

Adding to 31321 its reverse (12313), we get a palindrome (43634).

The spelling of 31321 in words is "thirty-one thousand, three hundred twenty-one".