31128091 has 2 divisors, whose sum is σ = 31128092. Its totient is φ = 31128090.

The previous prime is 31128079. The next prime is 31128127. The reversal of 31128091 is 19082113.

It is a weak prime.

It is an emirp because it is prime and its reverse (19082113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31128091 - 2⁵ = 31128059 is a prime.

It is equal to p_1923361 and since 31128091 and 1923361 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (31128011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15564045 + 15564046.

It is an arithmetic number, because the mean of its divisors is an integer number (15564046).

Almost surely, 2^31128091 is an apocalyptic number.

31128091 is a deficient number, since it is larger than the sum of its proper divisors (1).

31128091 is an equidigital number, since it uses as much as digits as its factorization.

31128091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 31128091 is about 5579.2554162720. The cubic root of 31128091 is about 314.5701401286.

The spelling of 31128091 in words is "thirty-one million, one hundred twenty-eight thousand, ninety-one".