19666681387920 has 640 divisors, whose sum is σ = 79842569748480. Its totient is φ = 4356110223360.

The previous prime is 19666681387849. The next prime is 19666681387921. The reversal of 19666681387920 is 2978318666691.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is not an unprimeable number, because it can be changed into a prime (19666681387921) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 82451230 + ... + 82689410.

It is an arithmetic number, because the mean of its divisors is an integer number (124754015232).

Almost surely, 2^{19666681387920} is an apocalyptic number.

19666681387920 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 19666681387920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39921284874240).

19666681387920 is an abundant number, since it is smaller than the sum of its proper divisors (60175888360560).

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

19666681387920 is a wasteful number, since it uses less digits than its factorization.

19666681387920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238380 (or 238368 counting only the distinct ones).

The product of its (nonzero) digits is 282175488, while the sum is 72.

The spelling of 19666681387920 in words is "nineteen trillion, six hundred sixty-six billion, six hundred eighty-one million, three hundred eighty-seven thousand, nine hundred twenty".