21240545280 has 544 divisors, whose sum is σ = 76100871168. Its totient is φ = 5033164800.

The previous prime is 21240545273. The next prime is 21240545351. The reversal of 21240545280 is 8254504212.

It is a tau number, because it is divible by the number of its divisors (544).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 518062060 + ... + 518062100.

Almost surely, 2^21240545280 is an apocalyptic number.

21240545280 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 21240545280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38050435584).

21240545280 is an abundant number, since it is smaller than the sum of its proper divisors (54860325888).

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

21240545280 is an equidigital number, since it uses as much as digits as its factorization.

21240545280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129 (or 99 counting only the distinct ones).

The product of its (nonzero) digits is 25600, while the sum is 33.

The spelling of 21240545280 in words is "twenty-one billion, two hundred forty million, five hundred forty-five thousand, two hundred eighty".