128121529 has 4 divisors (see below), whose sum is σ = 128187684. Its totient is φ = 128055376.

The previous prime is 128121527. The next prime is 128121557. The reversal of 128121529 is 925121821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 56972304 + 71149225 = 7548^2 + 8435^2 .

It is a cyclic number.

It is not a de Polignac number, because 128121529 - 2¹ = 128121527 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 128121529.

It is not an unprimeable number, because it can be changed into a prime (128121527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30082 + ... + 34075.

It is an arithmetic number, because the mean of its divisors is an integer number (32046921).

Almost surely, 2^128121529 is an apocalyptic number.

It is an amenable number.

128121529 is a deficient number, since it is larger than the sum of its proper divisors (66155).

128121529 is an equidigital number, since it uses as much as digits as its factorization.

128121529 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66154.

The product of its digits is 2880, while the sum is 31.

The square root of 128121529 is about 11319.0780985025. The cubic root of 128121529 is about 504.1278663247.

It can be divided in two parts, 12812 and 1529, that added together give a palindrome (14341).

The spelling of 128121529 in words is "one hundred twenty-eight million, one hundred twenty-one thousand, five hundred twenty-nine".