128637881 has 8 divisors (see below), whose sum is σ = 133203720. Its totient is φ = 124080768.

The previous prime is 128637857. The next prime is 128637889. The reversal of 128637881 is 188736821.

It can be written as a sum of positive squares in 4 ways, for example, as 19600 + 128618281 = 140^2 + 11341^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 128637881 - 2²² = 124443577 is a prime.

It is a super-2 number, since 2×128637881² = 33095408856340322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128637889) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46715 + ... + 49391.

It is an arithmetic number, because the mean of its divisors is an integer number (16650465).

Almost surely, 2^128637881 is an apocalyptic number.

It is an amenable number.

128637881 is a deficient number, since it is larger than the sum of its proper divisors (4565839).

128637881 is a wasteful number, since it uses less digits than its factorization.

128637881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4363.

The product of its digits is 129024, while the sum is 44.

The square root of 128637881 is about 11341.8640884116. The cubic root of 128637881 is about 504.8041994911.

The spelling of 128637881 in words is "one hundred twenty-eight million, six hundred thirty-seven thousand, eight hundred eighty-one".