31321399 has 2 divisors, whose sum is σ = 31321400. Its totient is φ = 31321398.

The previous prime is 31321387. The next prime is 31321427. The reversal of 31321399 is 99312313.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31321399 - 2¹³ = 31313207 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31321399.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31321309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15660699 + 15660700.

It is an arithmetic number, because the mean of its divisors is an integer number (15660700).

Almost surely, 2^31321399 is an apocalyptic number.

31321399 is a deficient number, since it is larger than the sum of its proper divisors (1).

31321399 is an equidigital number, since it uses as much as digits as its factorization.

31321399 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4374, while the sum is 31.

The square root of 31321399 is about 5596.5524209106. The cubic root of 31321399 is about 315.2199656191.

It can be divided in two parts, 313 and 21399, that added together give a palindrome (21712).

The spelling of 31321399 in words is "thirty-one million, three hundred twenty-one thousand, three hundred ninety-nine".