19998785537640 has 1728 divisors, whose sum is σ = 86464235894400. Its totient is φ = 3966005514240.

The previous prime is 19998785537623. The next prime is 19998785537651. The reversal of 19998785537640 is 4673558789991.

19998785537640 is a `hidden beast` number, since 1 + 9 + 9 + 9 + 8 + 78 + 5 + 537 + 6 + 4 + 0 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 19998785537640.

It is an unprimeable number.

It is a polite number, since it can be written in 431 ways as a sum of consecutive naturals, for example, 19625893051 + ... + 19625894069.

It is an arithmetic number, because the mean of its divisors is an integer number (50037173550).

Almost surely, 2^{19998785537640} is an apocalyptic number.

19998785537640 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 19998785537640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43232117947200).

19998785537640 is an abundant number, since it is smaller than the sum of its proper divisors (66465450356760).

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

19998785537640 is a wasteful number, since it uses less digits than its factorization.

19998785537640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1208 (or 1133 counting only the distinct ones).

The product of its (nonzero) digits is 4115059200, while the sum is 81.

The spelling of 19998785537640 in words is "nineteen trillion, nine hundred ninety-eight billion, seven hundred eighty-five million, five hundred thirty-seven thousand, six hundred forty".