31813321 has 2 divisors, whose sum is σ = 31813322. Its totient is φ = 31813320.

The previous prime is 31813297. The next prime is 31813337. The reversal of 31813321 is 12331813.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31809600 + 3721 = 5640^2 + 61^2 .

It is a cyclic number.

It is not a de Polignac number, because 31813321 - 2¹⁹ = 31289033 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 31813292 and 31813301.

It is not a weakly prime, because it can be changed into another prime (31813021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15906660 + 15906661.

It is an arithmetic number, because the mean of its divisors is an integer number (15906661).

Almost surely, 2^31813321 is an apocalyptic number.

It is an amenable number.

31813321 is a deficient number, since it is larger than the sum of its proper divisors (1).

31813321 is an equidigital number, since it uses as much as digits as its factorization.

31813321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 22.

The square root of 31813321 is about 5640.3298662401. The cubic root of 31813321 is about 316.8616425608.

The spelling of 31813321 in words is "thirty-one million, eight hundred thirteen thousand, three hundred twenty-one".