19820 has 12 divisors (see below), whose sum is σ = 41664. Its totient is φ = 7920.

The previous prime is 19819. The next prime is 19841. The reversal of 19820 is 2891.

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 991 = 19820 / (1 + 9 + 8 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 19792 and 19801.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 19820.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 476 + ... + 515.

It is an arithmetic number, because the mean of its divisors is an integer number (3472).

2¹⁹⁸²⁰ is an apocalyptic number.

19820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19820 is an abundant number, since it is smaller than the sum of its proper divisors (21844).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20832).

19820 is a wasteful number, since it uses less digits than its factorization.

19820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1000 (or 998 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 19820 is about 140.7835217630. The cubic root of 19820 is about 27.0624981110.

The spelling of 19820 in words is "nineteen thousand, eight hundred twenty".