21518801280 has 768 divisors, whose sum is σ = 84172032000. Its totient is φ = 5188976640.

The previous prime is 21518801279. The next prime is 21518801327. The reversal of 21518801280 is 8210881512.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 154811451 + ... + 154811589.

It is an arithmetic number, because the mean of its divisors is an integer number (109599000).

Almost surely, 2^21518801280 is an apocalyptic number.

21518801280 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 21518801280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42086016000).

21518801280 is an abundant number, since it is smaller than the sum of its proper divisors (62653230720).

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

21518801280 is a wasteful number, since it uses less digits than its factorization.

21518801280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 232 (or 197 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 36.

The spelling of 21518801280 in words is "twenty-one billion, five hundred eighteen million, eight hundred one thousand, two hundred eighty".