128380561 has 2 divisors, whose sum is σ = 128380562. Its totient is φ = 128380560.

The previous prime is 128380541. The next prime is 128380573. The reversal of 128380561 is 165083821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 127690000 + 690561 = 11300^2 + 831^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128380561 is a prime.

It is not a weakly prime, because it can be changed into another prime (128380541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64190280 + 64190281.

It is an arithmetic number, because the mean of its divisors is an integer number (64190281).

Almost surely, 2^128380561 is an apocalyptic number.

It is an amenable number.

128380561 is a deficient number, since it is larger than the sum of its proper divisors (1).

128380561 is an equidigital number, since it uses as much as digits as its factorization.

128380561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11520, while the sum is 34.

The square root of 128380561 is about 11330.5145955513. The cubic root of 128380561 is about 504.4673808072.

It can be divided in two parts, 128 and 380561, that added together give a square (380689 = 617²).

The spelling of 128380561 in words is "one hundred twenty-eight million, three hundred eighty thousand, five hundred sixty-one".