100820 has 18 divisors (see below), whose sum is σ = 214746. Its totient is φ = 39760.

The previous prime is 100811. The next prime is 100823. The reversal of 100820 is 28001.

It can be written as a sum of positive squares in only one way, i.e., 80656 + 20164 = 284^2 + 142^2 .

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 100820.

It is not an unprimeable number, because it can be changed into a prime (100823) by changing a digit.

100820 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 5 ways as a sum of consecutive naturals, for example, 1385 + ... + 1455.

2¹⁰⁰⁸²⁰ is an apocalyptic number.

100820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

100820 is an abundant number, since it is smaller than the sum of its proper divisors (113926).

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

100820 is an equidigital number, since it uses as much as digits as its factorization.

100820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151 (or 78 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 100820 is about 317.5216528050. The cubic root of 100820 is about 46.5424132238.

Adding to 100820 its reverse (28001), we get a palindrome (128821).

The spelling of 100820 in words is "one hundred thousand, eight hundred twenty".