128645641877 has 4 divisors (see below), whose sum is σ = 128646530316. Its totient is φ = 128644753440.

The previous prime is 128645641841. The next prime is 128645641897. The reversal of 128645641877 is 778146546821.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 778146546821 = 7 ⋅111163792403.

It can be written as a sum of positive squares in 2 ways, for example, as 69830176516 + 58815465361 = 264254^2 + 242519^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128645641877 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 (128645641897) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 171008 + ... + 535289.

It is an arithmetic number, because the mean of its divisors is an integer number (32161632579).

Almost surely, 2^128645641877 is an apocalyptic number.

It is an amenable number.

128645641877 is a deficient number, since it is larger than the sum of its proper divisors (888439).

128645641877 is an equidigital number, since it uses as much as digits as its factorization.

128645641877 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 888438.

The product of its digits is 18063360, while the sum is 59.

The spelling of 128645641877 in words is "one hundred twenty-eight billion, six hundred forty-five million, six hundred forty-one thousand, eight hundred seventy-seven".