21780218580 has 96 divisors (see below), whose sum is σ = 63542102400. Its totient is φ = 5567374848.

The previous prime is 21780218557. The next prime is 21780218587. The reversal of 21780218580 is 8581208712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21780218587) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 196834 + ... + 286886.

It is an arithmetic number, because the mean of its divisors is an integer number (661896900).

Almost surely, 2^21780218580 is an apocalyptic number.

21780218580 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 21780218580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31771051200).

21780218580 is an abundant number, since it is smaller than the sum of its proper divisors (41761883820).

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

21780218580 is a wasteful number, since it uses less digits than its factorization.

21780218580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90233 (or 90231 counting only the distinct ones).

The product of its (nonzero) digits is 71680, while the sum is 42.

The spelling of 21780218580 in words is "twenty-one billion, seven hundred eighty million, two hundred eighteen thousand, five hundred eighty".