19721487937536 has 1872 divisors, whose sum is σ = 78688014451200. Its totient is φ = 4849795399680.

The previous prime is 19721487937519. The next prime is 19721487937561. The reversal of 19721487937536 is 63573978412791.

19721487937536 is a `hidden beast` number, since 1 + 9 + 7 + 2 + 1 + 4 + 87 + 9 + 3 + 7 + 536 = 666.

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

It is a congruent number.

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 143 ways as a sum of consecutive naturals, for example, 12458298601 + ... + 12458300183.

Almost surely, 2^{19721487937536} is an apocalyptic number.

19721487937536 is a gapful number since it is divisible by the number (16) 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 19721487937536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39344007225600).

19721487937536 is an abundant number, since it is smaller than the sum of its proper divisors (58966526513664).

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

19721487937536 is a wasteful number, since it uses less digits than its factorization.

19721487937536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1671 (or 1625 counting only the distinct ones).

The product of its digits is 480090240, while the sum is 72.

The spelling of 19721487937536 in words is "nineteen trillion, seven hundred twenty-one billion, four hundred eighty-seven million, nine hundred thirty-seven thousand, five hundred thirty-six".