128918861 has 2 divisors, whose sum is σ = 128918862. Its totient is φ = 128918860.

The previous prime is 128918851. The next prime is 128918893. The reversal of 128918861 is 168819821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 106213636 + 22705225 = 10306^2 + 4765^2 .

It is an emirp because it is prime and its reverse (168819821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 128918861 - 2¹⁰ = 128917837 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128918821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64459430 + 64459431.

It is an arithmetic number, because the mean of its divisors is an integer number (64459431).

Almost surely, 2^128918861 is an apocalyptic number.

It is an amenable number.

128918861 is a deficient number, since it is larger than the sum of its proper divisors (1).

128918861 is an equidigital number, since it uses as much as digits as its factorization.

128918861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55296, while the sum is 44.

The square root of 128918861 is about 11354.2441844449. The cubic root of 128918861 is about 505.1714752779.

The spelling of 128918861 in words is "one hundred twenty-eight million, nine hundred eighteen thousand, eight hundred sixty-one".