128917 has 4 divisors (see below), whose sum is σ = 129996. Its totient is φ = 127840.

The previous prime is 128903. The next prime is 128923. The reversal of 128917 is 719821.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 77841 + 51076 = 279^2 + 226^2 .

It is a cyclic number.

It is not a de Polignac number, because 128917 - 2¹⁵ = 96149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128987) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 334 + ... + 607.

It is an arithmetic number, because the mean of its divisors is an integer number (32499).

2¹²⁸⁹¹⁷ is an apocalyptic number.

It is an amenable number.

128917 is a deficient number, since it is larger than the sum of its proper divisors (1079).

128917 is an equidigital number, since it uses as much as digits as its factorization.

128917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1078.

The product of its digits is 1008, while the sum is 28.

The square root of 128917 is about 359.0501357749. The cubic root of 128917 is about 50.5169044476.

The spelling of 128917 in words is "one hundred twenty-eight thousand, nine hundred seventeen".