128981 has 2 divisors, whose sum is σ = 128982. Its totient is φ = 128980.

The previous prime is 128971. The next prime is 128983. The reversal of 128981 is 189821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 128881 + 100 = 359^2 + 10^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128981 is a prime.

It is a super-2 number, since 2×128981² = 33272196722, which contains 22 as substring.

Together with 128983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 128981.

It is not a weakly prime, because it can be changed into another prime (128983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64490 + 64491.

It is an arithmetic number, because the mean of its divisors is an integer number (64491).

2¹²⁸⁹⁸¹ is an apocalyptic number.

It is an amenable number.

128981 is a deficient number, since it is larger than the sum of its proper divisors (1).

128981 is an equidigital number, since it uses as much as digits as its factorization.

128981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 29.

The square root of 128981 is about 359.1392487601. The cubic root of 128981 is about 50.5252626600.

It can be divided in two parts, 1 and 28981, that added together give a palindrome (28982).

The spelling of 128981 in words is "one hundred twenty-eight thousand, nine hundred eighty-one".