21210234240 has 256 divisors, whose sum is σ = 72981881280. Its totient is φ = 5208539136.

The previous prime is 21210234239. The next prime is 21210234289. The reversal of 21210234240 is 4243201212.

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, 14800564 + ... + 14801996.

Almost surely, 2^21210234240 is an apocalyptic number.

21210234240 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 21210234240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36490940640).

21210234240 is an abundant number, since it is smaller than the sum of its proper divisors (51771647040).

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

21210234240 is a wasteful number, since it uses less digits than its factorization.

21210234240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2061 (or 2049 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 21.

Adding to 21210234240 its reverse (4243201212), we get a palindrome (25453435452).

The spelling of 21210234240 in words is "twenty-one billion, two hundred ten million, two hundred thirty-four thousand, two hundred forty".