128661767797 has 4 divisors (see below), whose sum is σ = 128664164556. Its totient is φ = 128659371040.

The previous prime is 128661767761. The next prime is 128661767803. The reversal of 128661767797 is 797767166821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 68808634596 + 59853133201 = 262314^2 + 244649^2 .

It is a cyclic number.

It is not a de Polignac number, because 128661767797 - 2⁷ = 128661767669 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128661767497) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1115968 + ... + 1225849.

It is an arithmetic number, because the mean of its divisors is an integer number (32166041139).

Almost surely, 2^128661767797 is an apocalyptic number.

It is an amenable number.

128661767797 is a deficient number, since it is larger than the sum of its proper divisors (2396759).

128661767797 is an equidigital number, since it uses as much as digits as its factorization.

128661767797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2396758.

The product of its digits is 74680704, while the sum is 67.

The spelling of 128661767797 in words is "one hundred twenty-eight billion, six hundred sixty-one million, seven hundred sixty-seven thousand, seven hundred ninety-seven".