31128997 has 2 divisors, whose sum is σ = 31128998. Its totient is φ = 31128996.

The previous prime is 31128961. The next prime is 31129001. The reversal of 31128997 is 79982113.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30758116 + 370881 = 5546^2 + 609^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31128997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31128917) by changing a digit.

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

It is an upside-down number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15564498 + 15564499.

It is an arithmetic number, because the mean of its divisors is an integer number (15564499).

Almost surely, 2^31128997 is an apocalyptic number.

It is an amenable number.

31128997 is a deficient number, since it is larger than the sum of its proper divisors (1).

31128997 is an equidigital number, since it uses as much as digits as its factorization.

31128997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27216, while the sum is 40.

The square root of 31128997 is about 5579.3366093112. The cubic root of 31128997 is about 314.5731920106.

The spelling of 31128997 in words is "thirty-one million, one hundred twenty-eight thousand, nine hundred ninety-seven".