128931 has 8 divisors (see below), whose sum is σ = 187584. Its totient is φ = 78120.

The previous prime is 128923. The next prime is 128939. The reversal of 128931 is 139821.

It is an interprime number because it is at equal distance from previous prime (128923) and next prime (128939).

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

It is not a de Polignac number, because 128931 - 2³ = 128923 is a prime.

It is a super-2 number, since 2×128931² = 33246405522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

128931 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128939) 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, 1921 + ... + 1986.

It is an arithmetic number, because the mean of its divisors is an integer number (23448).

2¹²⁸⁹³¹ is an apocalyptic number.

128931 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

128931 is a deficient number, since it is larger than the sum of its proper divisors (58653).

128931 is a wasteful number, since it uses less digits than its factorization.

128931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3921.

The product of its digits is 432, while the sum is 24.

The square root of 128931 is about 359.0696311302. The cubic root of 128931 is about 50.5187330429.

The spelling of 128931 in words is "one hundred twenty-eight thousand, nine hundred thirty-one".