128757221 has 2 divisors, whose sum is σ = 128757222. Its totient is φ = 128757220.

The previous prime is 128757199. The next prime is 128757241. The reversal of 128757221 is 122757821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 111534721 + 17222500 = 10561^2 + 4150^2 .

It is a cyclic number.

It is not a de Polignac number, because 128757221 - 2⁶ = 128757157 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128757241) 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 as a sum of consecutive naturals, namely, 64378610 + 64378611.

It is an arithmetic number, because the mean of its divisors is an integer number (64378611).

Almost surely, 2^128757221 is an apocalyptic number.

It is an amenable number.

128757221 is a deficient number, since it is larger than the sum of its proper divisors (1).

128757221 is an equidigital number, since it uses as much as digits as its factorization.

128757221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15680, while the sum is 35.

The square root of 128757221 is about 11347.1239087268. The cubic root of 128757221 is about 504.9602569776.

The spelling of 128757221 in words is "one hundred twenty-eight million, seven hundred fifty-seven thousand, two hundred twenty-one".