21381780384 has 96 divisors (see below), whose sum is σ = 62531663040. Its totient is φ = 7108045056.

The previous prime is 21381780367. The next prime is 21381780419. The reversal of 21381780384 is 48308718312.

It is a tau number, because it is divible by the number of its divisors (96).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 289099 + ... + 355445.

It is an arithmetic number, because the mean of its divisors is an integer number (651371490).

Almost surely, 2^21381780384 is an apocalyptic number.

21381780384 is a gapful number since it is divisible by the number (24) 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 21381780384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31265831520).

21381780384 is an abundant number, since it is smaller than the sum of its proper divisors (41149882656).

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

21381780384 is a wasteful number, since it uses less digits than its factorization.

21381780384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66739 (or 66725 counting only the distinct ones).

The product of its (nonzero) digits is 258048, while the sum is 45.

The spelling of 21381780384 in words is "twenty-one billion, three hundred eighty-one million, seven hundred eighty thousand, three hundred eighty-four".