128915561 has 2 divisors, whose sum is σ = 128915562. Its totient is φ = 128915560.

The previous prime is 128915503. The next prime is 128915581. The reversal of 128915561 is 165519821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 117592336 + 11323225 = 10844^2 + 3365^2 .

It is an emirp because it is prime and its reverse (165519821) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128915561 is a prime.

It is not a weakly prime, because it can be changed into another prime (128915581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64457780 + 64457781.

It is an arithmetic number, because the mean of its divisors is an integer number (64457781).

Almost surely, 2^128915561 is an apocalyptic number.

It is an amenable number.

128915561 is a deficient number, since it is larger than the sum of its proper divisors (1).

128915561 is an equidigital number, since it uses as much as digits as its factorization.

128915561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21600, while the sum is 38.

The square root of 128915561 is about 11354.0988634061. The cubic root of 128915561 is about 505.1671648662.

The spelling of 128915561 in words is "one hundred twenty-eight million, nine hundred fifteen thousand, five hundred sixty-one".