128638817 has 2 divisors, whose sum is σ = 128638818. Its totient is φ = 128638816.

The previous prime is 128638789. The next prime is 128638831. The reversal of 128638817 is 718836821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 125238481 + 3400336 = 11191^2 + 1844^2 .

It is an emirp because it is prime and its reverse (718836821) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128638817 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (128638837) 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 as a sum of consecutive naturals, namely, 64319408 + 64319409.

It is an arithmetic number, because the mean of its divisors is an integer number (64319409).

Almost surely, 2^128638817 is an apocalyptic number.

It is an amenable number.

128638817 is a deficient number, since it is larger than the sum of its proper divisors (1).

128638817 is an equidigital number, since it uses as much as digits as its factorization.

128638817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 129024, while the sum is 44.

The square root of 128638817 is about 11341.9053513949. The cubic root of 128638817 is about 504.8054238469.

The spelling of 128638817 in words is "one hundred twenty-eight million, six hundred thirty-eight thousand, eight hundred seventeen".