19800864 has 72 divisors (see below), whose sum is σ = 56756700. Its totient is φ = 6547968.

The previous prime is 19800817. The next prime is 19800871. The reversal of 19800864 is 46800891.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 16160400 + 3640464 = 4020^2 + 1908^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 56562 + ... + 56910.

Almost surely, 2^19800864 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 19800864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28378350).

19800864 is an abundant number, since it is smaller than the sum of its proper divisors (36955836).

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

19800864 is a wasteful number, since it uses less digits than its factorization.

19800864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 562 (or 551 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 19800864 is about 4449.8161759785. The cubic root of 19800864 is about 270.5378578812.

The spelling of 19800864 in words is "nineteen million, eight hundred thousand, eight hundred sixty-four".