31321321 has 2 divisors, whose sum is σ = 31321322. Its totient is φ = 31321320.

The previous prime is 31321319. The next prime is 31321349. The reversal of 31321321 is 12312313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18619225 + 12702096 = 4315^2 + 3564^2 .

It is a cyclic number.

It is not a de Polignac number, because 31321321 - 2¹ = 31321319 is a prime.

Together with 31321319, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 31321295 and 31321304.

It is not a weakly prime, because it can be changed into another prime (31921321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15660660 + 15660661.

It is an arithmetic number, because the mean of its divisors is an integer number (15660661).

Almost surely, 2^31321321 is an apocalyptic number.

It is an amenable number.

31321321 is a deficient number, since it is larger than the sum of its proper divisors (1).

31321321 is an equidigital number, since it uses as much as digits as its factorization.

31321321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108, while the sum is 16.

The square root of 31321321 is about 5596.5454523304. The cubic root of 31321321 is about 315.2197039537.

Adding to 31321321 its reverse (12312313), we get a palindrome (43633634).

The spelling of 31321321 in words is "thirty-one million, three hundred twenty-one thousand, three hundred twenty-one".