128817581 has 2 divisors, whose sum is σ = 128817582. Its totient is φ = 128817580.

The previous prime is 128817541. The next prime is 128817589. The reversal of 128817581 is 185718821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69388900 + 59428681 = 8330^2 + 7709^2 .

It is an emirp because it is prime and its reverse (185718821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 128817581 - 2¹⁰ = 128816557 is a prime.

It is a super-2 number, since 2×128817581² = 33187938349383122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128817589) 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, 64408790 + 64408791.

It is an arithmetic number, because the mean of its divisors is an integer number (64408791).

Almost surely, 2^128817581 is an apocalyptic number.

It is an amenable number.

128817581 is a deficient number, since it is larger than the sum of its proper divisors (1).

128817581 is an equidigital number, since it uses as much as digits as its factorization.

128817581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 35840, while the sum is 41.

The square root of 128817581 is about 11349.7833018961. The cubic root of 128817581 is about 505.0391512959.

The spelling of 128817581 in words is "one hundred twenty-eight million, eight hundred seventeen thousand, five hundred eighty-one".