31128439 has 2 divisors, whose sum is σ = 31128440. Its totient is φ = 31128438.

The previous prime is 31128413. The next prime is 31128457. The reversal of 31128439 is 93482113.

It is a strong prime.

It is an emirp because it is prime and its reverse (93482113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31128439 - 2¹³ = 31120247 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31128439.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31128469) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15564219 + 15564220.

It is an arithmetic number, because the mean of its divisors is an integer number (15564220).

Almost surely, 2^31128439 is an apocalyptic number.

31128439 is a deficient number, since it is larger than the sum of its proper divisors (1).

31128439 is an equidigital number, since it uses as much as digits as its factorization.

31128439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 31.

The square root of 31128439 is about 5579.2866031420. The cubic root of 31128439 is about 314.5713123817.

The spelling of 31128439 in words is "thirty-one million, one hundred twenty-eight thousand, four hundred thirty-nine".