19740 has 48 divisors (see below), whose sum is σ = 64512. Its totient is φ = 4416.

The previous prime is 19739. The next prime is 19751. The reversal of 19740 is 4791.

Added to its reverse (4791) it gives a triangular number (24531 = T₂₂₁).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a nialpdrome in base 12.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 397 + ... + 443.

It is an arithmetic number, because the mean of its divisors is an integer number (1344).

2¹⁹⁷⁴⁰ is an apocalyptic number.

19740 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a pronic number, being equal to 140×141.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32256).

19740 is an abundant number, since it is smaller than the sum of its proper divisors (44772).

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

19740 is a wasteful number, since it uses less digits than its factorization.

19740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66 (or 64 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 19740 is about 140.4991103175. The cubic root of 19740 is about 27.0260379818.

Adding to 19740 its reverse (4791), we get a triangular number (24531 = T₂₂₁).

The spelling of 19740 in words is "nineteen thousand, seven hundred forty".