21721448268 has 288 divisors, whose sum is σ = 62925408000. Its totient is φ = 6511497984.

The previous prime is 21721448263. The next prime is 21721448279. The reversal of 21721448268 is 86284412712.

It is not an unprimeable number, because it can be changed into a prime (21721448263) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 145781458 + ... + 145781606.

It is an arithmetic number, because the mean of its divisors is an integer number (218491000).

Almost surely, 2^21721448268 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 21721448268, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31462704000).

21721448268 is an abundant number, since it is smaller than the sum of its proper divisors (41203959732).

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

21721448268 is a wasteful number, since it uses less digits than its factorization.

21721448268 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403 (or 389 counting only the distinct ones).

The product of its digits is 344064, while the sum is 45.

The spelling of 21721448268 in words is "twenty-one billion, seven hundred twenty-one million, four hundred forty-eight thousand, two hundred sixty-eight".