It is a nialpdrome in base 6, base 8 and base 15.
It is a zygodrome in base 6.
It is an unprimeable number.
27720 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
It is the 54-th tetrahedral number.
27720 is a highly composite number, because it has more divisors than any smaller number.
27720 is a superabundant number, because it has a larger abundancy index than any smaller number.
227720 is an apocalyptic number.
27720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 27720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (56160).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
27720 is a wasteful number, since it uses less digits than its factorization.
27720 is an evil number, because the sum of its binary digits is even.
The square root of 27720 is about 166.4932431061. The cubic root of 27720 is about 30.2643308006.
27720 divided by its sum of digits (18) gives a triangular number (1540 = T55).
The spelling of 27720 in words is "twenty-seven thousand, seven hundred twenty", and thus it is an iban number.