128508661881 has 6 divisors (see below), whose sum is σ = 185623622730. Its totient is φ = 85672441248.

The previous prime is 128508661859. The next prime is 128508661927. The reversal of 128508661881 is 188166805821.

128508661881 is a `hidden beast` number, since 12 + 8 + 5 + 0 + 8 + 6 + 618 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 71404390656 + 57104271225 = 267216^2 + 238965^2 .

It is not a de Polignac number, because 128508661881 - 2²¹ = 128506564729 is a prime.

It is a super-2 number, since 2×128508661881² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (128508661681) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7139370096 + ... + 7139370113.

It is an arithmetic number, because the mean of its divisors is an integer number (30937270455).

Almost surely, 2^128508661881 is an apocalyptic number.

It is an amenable number.

128508661881 is a deficient number, since it is larger than the sum of its proper divisors (57114960849).

128508661881 is a wasteful number, since it uses less digits than its factorization.

128508661881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14278740215 (or 14278740212 counting only the distinct ones).

The product of its (nonzero) digits is 1474560, while the sum is 54.

The spelling of 128508661881 in words is "one hundred twenty-eight billion, five hundred eight million, six hundred sixty-one thousand, eight hundred eighty-one".