128961881 has 8 divisors (see below), whose sum is σ = 136731240. Its totient is φ = 121212928.

The previous prime is 128961853. The next prime is 128961883. The reversal of 128961881 is 188169821.

It can be written as a sum of positive squares in 4 ways, for example, as 33235225 + 95726656 = 5765^2 + 9784^2 .

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 128961881 - 2¹⁰ = 128960857 is a prime.

It is a super-2 number, since 2×128961881² = 33262333502116322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (128961883) 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, 9065 + ... + 18441.

It is an arithmetic number, because the mean of its divisors is an integer number (17091405).

Almost surely, 2^128961881 is an apocalyptic number.

It is an amenable number.

128961881 is a deficient number, since it is larger than the sum of its proper divisors (7769359).

128961881 is an equidigital number, since it uses as much as digits as its factorization.

128961881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10203.

The product of its digits is 55296, while the sum is 44.

The square root of 128961881 is about 11356.1384722096. The cubic root of 128961881 is about 505.2276606433.

The spelling of 128961881 in words is "one hundred twenty-eight million, nine hundred sixty-one thousand, eight hundred eighty-one".