19980 has 48 divisors (see below), whose sum is σ = 63840. Its totient is φ = 5184.
The previous prime is 19979. The next prime is 19991. The reversal of 19980 is 8991.
It is a Harshad number since it is a multiple of its sum of digits (27).
It is an unprimeable number.
It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 522 + ... + 558.
It is an arithmetic number, because the mean of its divisors is an integer number (1330).
219980 is an apocalyptic number.
19980 is a gapful number since it is divisible by the number (10) 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 19980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31920).
19980 is an abundant number, since it is smaller than the sum of its proper divisors (43860).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
19980 is a wasteful number, since it uses less digits than its factorization.
19980 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 55 (or 47 counting only the distinct ones).
The product of its (nonzero) digits is 648, while the sum is 27.
The square root of 19980 is about 141.3506278727. The cubic root of 19980 is about 27.1351250895.
It can be divided in two parts, 19 and 980, that added together give a palindrome (999).
The spelling of 19980 in words is "nineteen thousand, nine hundred eighty".
• e-mail: info -at- numbersaplenty.com • Privacy notice • done in 0.064 sec. • engine limits •