21721789284 has 96 divisors (see below), whose sum is σ = 55359607296. Its totient is φ = 6589071360.

The previous prime is 21721789241. The next prime is 21721789291. The reversal of 21721789284 is 48298712712.

It is a super-2 number, since 2×21721789284² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4098124 + ... + 4103420.

It is an arithmetic number, because the mean of its divisors is an integer number (576662576).

Almost surely, 2^21721789284 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 21721789284, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27679803648).

21721789284 is an abundant number, since it is smaller than the sum of its proper divisors (33637818012).

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

21721789284 is a wasteful number, since it uses less digits than its factorization.

21721789284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5685 (or 5683 counting only the distinct ones).

The product of its digits is 903168, while the sum is 51.

The spelling of 21721789284 in words is "twenty-one billion, seven hundred twenty-one million, seven hundred eighty-nine thousand, two hundred eighty-four".