21009889783512 has 288 divisors, whose sum is σ = 68843656627200. Its totient is φ = 6002816317344.

The previous prime is 21009889783471. The next prime is 21009889783517. The reversal of 21009889783512 is 21538798890012.

21009889783512 is a `hidden beast` number, since 2 + 100 + 9 + 8 + 8 + 9 + 7 + 8 + 3 + 512 = 666.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21009889783512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21009889783517) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 32351289 + ... + 32994327.

It is an arithmetic number, because the mean of its divisors is an integer number (239040474400).

Almost surely, 2^{21009889783512} 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 21009889783512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34421828313600).

21009889783512 is an abundant number, since it is smaller than the sum of its proper divisors (47833766843688).

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

21009889783512 is an frugal number, since it uses more digits than its factorization.

21009889783512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643095 (or 643051 counting only the distinct ones).

The product of its (nonzero) digits is 17418240, while the sum is 63.

The spelling of 21009889783512 in words is "twenty-one trillion, nine billion, eight hundred eighty-nine million, seven hundred eighty-three thousand, five hundred twelve".