19864 has 16 divisors (see below), whose sum is σ = 40320. Its totient is φ = 9120.

The previous prime is 19861. The next prime is 19867. The reversal of 19864 is 46891.

It is an interprime number because it is at equal distance from previous prime (19861) and next prime (19867).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19861) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 9 + ... + 199.

It is an arithmetic number, because the mean of its divisors is an integer number (2520).

2¹⁹⁸⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20160).

19864 is an abundant number, since it is smaller than the sum of its proper divisors (20456).

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

19864 is a wasteful number, since it uses less digits than its factorization.

19864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210 (or 206 counting only the distinct ones).

The product of its digits is 1728, while the sum is 28.

The square root of 19864 is about 140.9397034196. The cubic root of 19864 is about 27.0825093766.

It can be divided in two parts, 198 and 64, that added together give a palindrome (262).

The spelling of 19864 in words is "nineteen thousand, eight hundred sixty-four".