128730221 has 2 divisors, whose sum is σ = 128730222. Its totient is φ = 128730220.

The previous prime is 128730211. The next prime is 128730229. The reversal of 128730221 is 122037821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 88153321 + 40576900 = 9389^2 + 6370^2 .

It is a cyclic number.

It is not a de Polignac number, because 128730221 - 2⁶ = 128730157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128730229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64365110 + 64365111.

It is an arithmetic number, because the mean of its divisors is an integer number (64365111).

Almost surely, 2^128730221 is an apocalyptic number.

It is an amenable number.

128730221 is a deficient number, since it is larger than the sum of its proper divisors (1).

128730221 is an equidigital number, since it uses as much as digits as its factorization.

128730221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 128730221 is about 11345.9341175595. The cubic root of 128730221 is about 504.9249582970.

The spelling of 128730221 in words is "one hundred twenty-eight million, seven hundred thirty thousand, two hundred twenty-one".