128749 has 2 divisors, whose sum is σ = 128750. Its totient is φ = 128748.

The previous prime is 128747. The next prime is 128761. The reversal of 128749 is 947821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81225 + 47524 = 285^2 + 218^2 .

It is a cyclic number.

It is not a de Polignac number, because 128749 - 2¹ = 128747 is a prime.

Together with 128747, it forms a pair of twin primes.

It is a plaindrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 128749.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128747) 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, 64374 + 64375.

It is an arithmetic number, because the mean of its divisors is an integer number (64375).

2¹²⁸⁷⁴⁹ is an apocalyptic number.

It is an amenable number.

128749 is a deficient number, since it is larger than the sum of its proper divisors (1).

128749 is an equidigital number, since it uses as much as digits as its factorization.

128749 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4032, while the sum is 31.

The square root of 128749 is about 358.8161088914. The cubic root of 128749 is about 50.4949509706.

The spelling of 128749 in words is "one hundred twenty-eight thousand, seven hundred forty-nine".