It is a nialpdrome in base 12.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 20520.
20520 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
220520 is an apocalyptic number.
20520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.
20520 is the 72-nd decagonal number.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 20520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36000).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
20520 is a wasteful number, since it uses less digits than its factorization.
20520 is an evil number, because the sum of its binary digits is even.
The square root of 20520 is about 143.2480366358. The cubic root of 20520 is about 27.3774158123.
The spelling of 20520 in words is "twenty thousand, five hundred twenty".