21978823680 has 528 divisors, whose sum is σ = 83966433408. Its totient is φ = 5271552000.

The previous prime is 21978823661. The next prime is 21978823723. The reversal of 21978823680 is 8632887912.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (528).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 66401115 + ... + 66401445.

It is an arithmetic number, because the mean of its divisors is an integer number (159027336).

Almost surely, 2^21978823680 is an apocalyptic number.

21978823680 is a gapful number since it is divisible by the number (20) 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 21978823680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41983216704).

21978823680 is an abundant number, since it is smaller than the sum of its proper divisors (61987609728).

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

21978823680 is a wasteful number, since it uses less digits than its factorization.

21978823680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 504 (or 483 counting only the distinct ones).

The product of its (nonzero) digits is 2322432, while the sum is 54.

The spelling of 21978823680 in words is "twenty-one billion, nine hundred seventy-eight million, eight hundred twenty-three thousand, six hundred eighty".