128340521 has 2 divisors, whose sum is σ = 128340522. Its totient is φ = 128340520.

The previous prime is 128340479. The next prime is 128340533. The reversal of 128340521 is 125043821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 124634896 + 3705625 = 11164^2 + 1925^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128340521 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (128340551) 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, 64170260 + 64170261.

It is an arithmetic number, because the mean of its divisors is an integer number (64170261).

Almost surely, 2^128340521 is an apocalyptic number.

It is an amenable number.

128340521 is a deficient number, since it is larger than the sum of its proper divisors (1).

128340521 is an equidigital number, since it uses as much as digits as its factorization.

128340521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 128340521 is about 11328.7475477212. The cubic root of 128340521 is about 504.4149300466.

The spelling of 128340521 in words is "one hundred twenty-eight million, three hundred forty thousand, five hundred twenty-one".