19665918720 has 900 divisors, whose sum is σ = 83130542880. Its totient is φ = 4438167552.

The previous prime is 19665918719. The next prime is 19665918739. The reversal of 19665918720 is 2781956691.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 99 ways as a sum of consecutive naturals, for example, 248935641 + ... + 248935719.

Almost surely, 2^19665918720 is an apocalyptic number.

19665918720 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 19665918720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41565271440).

19665918720 is an abundant number, since it is smaller than the sum of its proper divisors (63464624160).

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

19665918720 is an frugal number, since it uses more digits than its factorization.

19665918720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140 (or 96 counting only the distinct ones).

The product of its (nonzero) digits is 1632960, while the sum is 54.

The spelling of 19665918720 in words is "nineteen billion, six hundred sixty-five million, nine hundred eighteen thousand, seven hundred twenty".