19718864 has 40 divisors (see below), whose sum is σ = 41976480. Its totient is φ = 8899200.

The previous prime is 19718857. The next prime is 19718879. The reversal of 19718864 is 46881791.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31547 + ... + 32165.

It is an arithmetic number, because the mean of its divisors is an integer number (1049412).

Almost surely, 2^19718864 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 19718864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20988240).

19718864 is an abundant number, since it is smaller than the sum of its proper divisors (22257616).

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

19718864 is a wasteful number, since it uses less digits than its factorization.

19718864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 819 (or 813 counting only the distinct ones).

The product of its digits is 96768, while the sum is 44.

The square root of 19718864 is about 4440.5927532256. The cubic root of 19718864 is about 270.1638876985.

The spelling of 19718864 in words is "nineteen million, seven hundred eighteen thousand, eight hundred sixty-four".