21537546240 has 560 divisors, whose sum is σ = 81498478608. Its totient is φ = 4855431168.

The previous prime is 21537546229. The next prime is 21537546259. The reversal of 21537546240 is 4264573512.

It is a tau number, because it is divible by the number of its divisors (560).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 295034844 + ... + 295034916.

Almost surely, 2^21537546240 is an apocalyptic number.

21537546240 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 21537546240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40749239304).

21537546240 is an abundant number, since it is smaller than the sum of its proper divisors (59960932368).

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

21537546240 is an frugal number, since it uses more digits than its factorization.

21537546240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135 (or 90 counting only the distinct ones).

The product of its (nonzero) digits is 201600, while the sum is 39.

The spelling of 21537546240 in words is "twenty-one billion, five hundred thirty-seven million, five hundred forty-six thousand, two hundred forty".