128644861 has 2 divisors, whose sum is σ = 128644862. Its totient is φ = 128644860.

The previous prime is 128644853. The next prime is 128644871. The reversal of 128644861 is 168446821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 90440100 + 38204761 = 9510^2 + 6181^2 .

It is a cyclic number.

It is not a de Polignac number, because 128644861 - 2³ = 128644853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128644871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64322430 + 64322431.

It is an arithmetic number, because the mean of its divisors is an integer number (64322431).

Almost surely, 2^128644861 is an apocalyptic number.

It is an amenable number.

128644861 is a deficient number, since it is larger than the sum of its proper divisors (1).

128644861 is an equidigital number, since it uses as much as digits as its factorization.

128644861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 73728, while the sum is 40.

The square root of 128644861 is about 11342.1717937968. The cubic root of 128644861 is about 504.8133296933.

The spelling of 128644861 in words is "one hundred twenty-eight million, six hundred forty-four thousand, eight hundred sixty-one".