19780 has 24 divisors (see below), whose sum is σ = 44352. Its totient is φ = 7392.

The previous prime is 19777. The next prime is 19793. The reversal of 19780 is 8791.

It is a plaindrome in base 7.

It is a nialpdrome in base 12.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 439 + ... + 481.

It is an arithmetic number, because the mean of its divisors is an integer number (1848).

2¹⁹⁷⁸⁰ is an apocalyptic number.

19780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

19780 is the 115-th pentagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22176).

19780 is an abundant number, since it is smaller than the sum of its proper divisors (24572).

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

19780 is a wasteful number, since it uses less digits than its factorization.

19780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75 (or 73 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 25.

The square root of 19780 is about 140.6413879340. The cubic root of 19780 is about 27.0442803350.

The spelling of 19780 in words is "nineteen thousand, seven hundred eighty".