21321974648 has 128 divisors (see below), whose sum is σ = 48071923200. Its totient is φ = 8770291200.

The previous prime is 21321974647. The next prime is 21321974701. The reversal of 21321974648 is 84647912312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321974647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2768483 + ... + 2776173.

It is an arithmetic number, because the mean of its divisors is an integer number (375561900).

Almost surely, 2^21321974648 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 21321974648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24035961600).

21321974648 is an abundant number, since it is smaller than the sum of its proper divisors (26749948552).

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

21321974648 is a wasteful number, since it uses less digits than its factorization.

21321974648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7813 (or 7809 counting only the distinct ones).

The product of its digits is 580608, while the sum is 47.

The spelling of 21321974648 in words is "twenty-one billion, three hundred twenty-one million, nine hundred seventy-four thousand, six hundred forty-eight".