31128909 has 16 divisors (see below), whose sum is σ = 47546880. Its totient is φ = 17745840.

The previous prime is 31128893. The next prime is 31128917. The reversal of 31128909 is 90982113.

It is not a de Polignac number, because 31128909 - 2⁴ = 31128893 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31128909.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31128509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8802 + ... + 11820.

It is an arithmetic number, because the mean of its divisors is an integer number (2971680).

Almost surely, 2^31128909 is an apocalyptic number.

It is an amenable number.

31128909 is a deficient number, since it is larger than the sum of its proper divisors (16417971).

31128909 is a wasteful number, since it uses less digits than its factorization.

31128909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3520.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 31128909 is about 5579.3287230634. The cubic root of 31128909 is about 314.5728955832.

It can be divided in two parts, 3112 and 8909, that added together give a palindrome (12021).

The spelling of 31128909 in words is "thirty-one million, one hundred twenty-eight thousand, nine hundred nine".