21818057720 has 64 divisors (see below), whose sum is σ = 52074226080. Its totient is φ = 8198701056.

The previous prime is 21818057663. The next prime is 21818057731. The reversal of 21818057720 is 2775081812.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 342632 + ... + 401288.

Almost surely, 2^21818057720 is an apocalyptic number.

21818057720 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 21818057720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26037113040).

21818057720 is an abundant number, since it is smaller than the sum of its proper divisors (30256168360).

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

21818057720 is a wasteful number, since it uses less digits than its factorization.

21818057720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59232 (or 59228 counting only the distinct ones).

The product of its (nonzero) digits is 62720, while the sum is 41.

The spelling of 21818057720 in words is "twenty-one billion, eight hundred eighteen million, fifty-seven thousand, seven hundred twenty".