21780440478720 has 2376 divisors, whose sum is σ = 99860305545000. Its totient is φ = 4368153968640.

The previous prime is 21780440478689. The next prime is 21780440478763. The reversal of 21780440478720 is 2787404408712.

21780440478720 is a `hidden beast` number, since 2 + 1 + 7 + 80 + 440 + 47 + 87 + 2 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 299217752064 + 21481222726656 = 547008^2 + 4634784^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 215 ways as a sum of consecutive naturals, for example, 7923039906 + ... + 7923042654.

It is an arithmetic number, because the mean of its divisors is an integer number (42028748125).

Almost surely, 2^{21780440478720} is an apocalyptic number.

21780440478720 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 21780440478720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49930152772500).

21780440478720 is an abundant number, since it is smaller than the sum of its proper divisors (78079865066280).

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

21780440478720 is a wasteful number, since it uses less digits than its factorization.

21780440478720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2845 (or 2806 counting only the distinct ones).

The product of its (nonzero) digits is 5619712, while the sum is 54.

The spelling of 21780440478720 in words is "twenty-one trillion, seven hundred eighty billion, four hundred forty million, four hundred seventy-eight thousand, seven hundred twenty".