128811931 has 8 divisors (see below), whose sum is σ = 132721664. Its totient is φ = 124960320.

The previous prime is 128811919. The next prime is 128811959. The reversal of 128811931 is 139118821.

It is a happy number.

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 128811931 - 2⁵ = 128811899 is a prime.

It is a super-2 number, since 2×128811931² = 33185027135897522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128811971) 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, 10011 + ... + 18916.

It is an arithmetic number, because the mean of its divisors is an integer number (16590208).

Almost surely, 2^128811931 is an apocalyptic number.

128811931 is a deficient number, since it is larger than the sum of its proper divisors (3909733).

128811931 is an equidigital number, since it uses as much as digits as its factorization.

128811931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29061.

The product of its digits is 3456, while the sum is 34.

The square root of 128811931 is about 11349.5343957362. The cubic root of 128811931 is about 505.0317674360.

The spelling of 128811931 in words is "one hundred twenty-eight million, eight hundred eleven thousand, nine hundred thirty-one".