20721087399936 has 768 divisors, whose sum is σ = 70407653621760. Its totient is φ = 5263294464000.

The previous prime is 20721087399923. The next prime is 20721087400003. The reversal of 20721087399936 is 63999378012702.

It is a tau number, because it is divible by the number of its divisors (768).

It is a Harshad number since it is a multiple of its sum of digits (66).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5223362625 + ... + 5223366591.

It is an arithmetic number, because the mean of its divisors is an integer number (91676632320).

Almost surely, 2^{20721087399936} 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 20721087399936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35203826810880).

20721087399936 is an abundant number, since it is smaller than the sum of its proper divisors (49686566221824).

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

20721087399936 is a wasteful number, since it uses less digits than its factorization.

20721087399936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4252 (or 4232 counting only the distinct ones).

The product of its (nonzero) digits is 61725888, while the sum is 66.

The spelling of 20721087399936 in words is "twenty trillion, seven hundred twenty-one billion, eighty-seven million, three hundred ninety-nine thousand, nine hundred thirty-six".