128961 has 24 divisors (see below), whose sum is σ = 224640. Its totient is φ = 69696.

The previous prime is 128959. The next prime is 128969. The reversal of 128961 is 169821.

128961 is nontrivially palindromic in base 11.

It is not a de Polignac number, because 128961 - 2¹ = 128959 is a prime.

It is not an unprimeable number, because it can be changed into a prime (128969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1405 + ... + 1493.

It is an arithmetic number, because the mean of its divisors is an integer number (9360).

2¹²⁸⁹⁶¹ is an apocalyptic number.

It is an amenable number.

128961 is a deficient number, since it is larger than the sum of its proper divisors (95679).

128961 is a wasteful number, since it uses less digits than its factorization.

128961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125 (or 122 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 128961 is about 359.1114033277. Note that the first 3 decimals coincide. The cubic root of 128961 is about 50.5226510157.

It can be divided in two parts, 128 and 961, that added together give a square (1089 = 33²).

The spelling of 128961 in words is "one hundred twenty-eight thousand, nine hundred sixty-one".