100840 has 16 divisors (see below), whose sum is σ = 226980. Its totient is φ = 40320.

The previous prime is 100829. The next prime is 100847. The reversal of 100840 is 48001.

100840 is nontrivially palindromic in base 7.

It can be written as a sum of positive squares in 2 ways, for example, as 81796 + 19044 = 286^2 + 138^2 .

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 100840.

It is not an unprimeable number, because it can be changed into a prime (100847) by changing a digit.

100840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1221 + ... + 1300.

2¹⁰⁰⁸⁴⁰ is an apocalyptic number.

100840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

100840 is an abundant number, since it is smaller than the sum of its proper divisors (126140).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

100840 is a wasteful number, since it uses less digits than its factorization.

100840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2532 (or 2528 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 100840 is about 317.5531451584. The cubic root of 100840 is about 46.5454906117.

Adding to 100840 its reverse (48001), we get a palindrome (148841).

The spelling of 100840 in words is "one hundred thousand, eight hundred forty".