21585780240 has 160 divisors (see below), whose sum is σ = 68489473536. Its totient is φ = 5621391360.

The previous prime is 21585780211. The next prime is 21585780247. The reversal of 21585780240 is 4208758512.

It is a Cunningham number, because it is equal to 146921²-1.

It is a junction number, because it is equal to n+sod(n) for n = 21585780192 and 21585780201.

It is not an unprimeable number, because it can be changed into a prime (21585780247) 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, 5875044 + ... + 5878716.

Almost surely, 2^21585780240 is an apocalyptic number.

21585780240 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 21585780240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34244736768).

21585780240 is an abundant number, since it is smaller than the sum of its proper divisors (46903693296).

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

21585780240 is a wasteful number, since it uses less digits than its factorization.

21585780240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4257 (or 4251 counting only the distinct ones).

The product of its (nonzero) digits is 179200, while the sum is 42.

The spelling of 21585780240 in words is "twenty-one billion, five hundred eighty-five million, seven hundred eighty thousand, two hundred forty".