18991979072640 has 1536 divisors, whose sum is σ = 80145154252800. Its totient is φ = 4207741157376.

The previous prime is 18991979072609. The next prime is 18991979072657. The reversal of 18991979072640 is 4627097919981.

18991979072640 is a `hidden beast` number, since 1 + 8 + 99 + 197 + 90 + 7 + 264 + 0 = 666.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 5474768826 + ... + 5474772294.

It is an arithmetic number, because the mean of its divisors is an integer number (52177834800).

Almost surely, 2^{18991979072640} is an apocalyptic number.

18991979072640 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 18991979072640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40072577126400).

18991979072640 is an abundant number, since it is smaller than the sum of its proper divisors (61153175180160).

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

18991979072640 is a wasteful number, since it uses less digits than its factorization.

18991979072640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3664 (or 3640 counting only the distinct ones).

The product of its (nonzero) digits is 123451776, while the sum is 72.

The spelling of 18991979072640 in words is "eighteen trillion, nine hundred ninety-one billion, nine hundred seventy-nine million, seventy-two thousand, six hundred forty".