128263581 has 20 divisors (see below), whose sum is σ = 194858400. Its totient is φ = 84056616.

The previous prime is 128263573. The next prime is 128263631. The reversal of 128263581 is 185362821.

It is a happy number.

128263581 is a `hidden beast` number, since 12 + 8 + 2 + 63 + 581 = 666.

It is not a de Polignac number, because 128263581 - 2³ = 128263573 is a prime.

It is a super-2 number, since 2×128263581² = 32903092421887122, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128263561) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 8641 + ... + 18198.

It is an arithmetic number, because the mean of its divisors is an integer number (9742920).

Almost surely, 2^128263581 is an apocalyptic number.

It is an amenable number.

128263581 is a deficient number, since it is larger than the sum of its proper divisors (66594819).

128263581 is an equidigital number, since it uses as much as digits as its factorization.

128263581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26910 (or 26901 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 128263581 is about 11325.3512528310. The cubic root of 128263581 is about 504.3141111666.

The spelling of 128263581 in words is "one hundred twenty-eight million, two hundred sixty-three thousand, five hundred eighty-one".