19665742800 has 720 divisors, whose sum is σ = 75976137216. Its totient is φ = 4325376000.

The previous prime is 19665742781. The next prime is 19665742807. The reversal of 19665742800 is 824756691.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 19665742800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19665742807) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 76520272 + ... + 76520528.

Almost surely, 2^19665742800 is an apocalyptic number.

19665742800 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 19665742800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37988068608).

19665742800 is an abundant number, since it is smaller than the sum of its proper divisors (56310394416).

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

19665742800 is a wasteful number, since it uses less digits than its factorization.

19665742800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 348 (or 326 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 48.

The spelling of 19665742800 in words is "nineteen billion, six hundred sixty-five million, seven hundred forty-two thousand, eight hundred".