31400321 has 2 divisors, whose sum is σ = 31400322. Its totient is φ = 31400320.

The previous prime is 31400297. The next prime is 31400323. The reversal of 31400321 is 12300413.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30958096 + 442225 = 5564^2 + 665^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31400321 is a prime.

Together with 31400323, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 31400296 and 31400305.

It is not a weakly prime, because it can be changed into another prime (31400323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15700160 + 15700161.

It is an arithmetic number, because the mean of its divisors is an integer number (15700161).

Almost surely, 2^31400321 is an apocalyptic number.

It is an amenable number.

31400321 is a deficient number, since it is larger than the sum of its proper divisors (1).

31400321 is an equidigital number, since it uses as much as digits as its factorization.

31400321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 31400321 is about 5603.5989328288. The cubic root of 31400321 is about 315.4845017389.

Adding to 31400321 its reverse (12300413), we get a palindrome (43700734).

The spelling of 31400321 in words is "thirty-one million, four hundred thousand, three hundred twenty-one".