21381571509936 has 320 divisors, whose sum is σ = 64128213626880. Its totient is φ = 6070700805120.

The previous prime is 21381571509889. The next prime is 21381571509937. The reversal of 21381571509936 is 63990517518312.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21381571509936.

It is not an unprimeable number, because it can be changed into a prime (21381571509937) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 813190806 + ... + 813217098.

It is an arithmetic number, because the mean of its divisors is an integer number (200400667584).

Almost surely, 2^{21381571509936} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21381571509936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32064106813440).

21381571509936 is an abundant number, since it is smaller than the sum of its proper divisors (42746642116944).

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

21381571509936 is a wasteful number, since it uses less digits than its factorization.

21381571509936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27224 (or 27218 counting only the distinct ones).

The product of its (nonzero) digits is 12247200, while the sum is 60.

The spelling of 21381571509936 in words is "twenty-one trillion, three hundred eighty-one billion, five hundred seventy-one million, five hundred nine thousand, nine hundred thirty-six".