19998720 has 288 divisors, whose sum is σ = 81768960. Its totient is φ = 4423680.

The previous prime is 19998701. The next prime is 19998721. The reversal of 19998720 is 2789991.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19998721) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 645105 + ... + 645135.

It is an arithmetic number, because the mean of its divisors is an integer number (283920).

Almost surely, 2^19998720 is an apocalyptic number.

19998720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19998720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40884480).

19998720 is an abundant number, since it is smaller than the sum of its proper divisors (61770240).

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

19998720 is a wasteful number, since it uses less digits than its factorization.

19998720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71 (or 48 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 45.

The square root of 19998720 is about 4471.9928443592. The cubic root of 19998720 is about 271.4359707784.

The spelling of 19998720 in words is "nineteen million, nine hundred ninety-eight thousand, seven hundred twenty".