31121399 has 2 divisors, whose sum is σ = 31121400. Its totient is φ = 31121398.

The previous prime is 31121393. The next prime is 31121401. The reversal of 31121399 is 99312113.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31121399 is a prime.

Together with 31121401, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31121393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15560699 + 15560700.

It is an arithmetic number, because the mean of its divisors is an integer number (15560700).

Almost surely, 2^31121399 is an apocalyptic number.

31121399 is a deficient number, since it is larger than the sum of its proper divisors (1).

31121399 is an equidigital number, since it uses as much as digits as its factorization.

31121399 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1458, while the sum is 29.

The square root of 31121399 is about 5578.6556624334. The cubic root of 31121399 is about 314.5475961372.

The spelling of 31121399 in words is "thirty-one million, one hundred twenty-one thousand, three hundred ninety-nine".