21017987107992 has 480 divisors, whose sum is σ = 67448563116480. Its totient is φ = 5911671185280.

The previous prime is 21017987107963. The next prime is 21017987108011. The reversal of 21017987107992 is 29970178971012.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 3015057067 + ... + 3015064037.

It is an arithmetic number, because the mean of its divisors is an integer number (140517839826).

Almost surely, 2^{21017987107992} 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 21017987107992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33724281558240).

21017987107992 is an abundant number, since it is smaller than the sum of its proper divisors (46430576008488).

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

21017987107992 is a wasteful number, since it uses less digits than its factorization.

21017987107992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7281 (or 7253 counting only the distinct ones).

The product of its (nonzero) digits is 8001504, while the sum is 63.

The spelling of 21017987107992 in words is "twenty-one trillion, seventeen billion, nine hundred eighty-seven million, one hundred seven thousand, nine hundred ninety-two".