21240299520 has 720 divisors, whose sum is σ = 84158238528. Its totient is φ = 5096079360.

The previous prime is 21240299473. The next prime is 21240299527. The reversal of 21240299520 is 2599204212.

21240299520 is a `hidden beast` number, since 2 + 1 + 2 + 40 + 2 + 99 + 520 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240299527) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 218972112 + ... + 218972208.

Almost surely, 2^21240299520 is an apocalyptic number.

21240299520 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 21240299520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42079119264).

21240299520 is an abundant number, since it is smaller than the sum of its proper divisors (62917939008).

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

21240299520 is an frugal number, since it uses more digits than its factorization.

21240299520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156 (or 118 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The spelling of 21240299520 in words is "twenty-one billion, two hundred forty million, two hundred ninety-nine thousand, five hundred twenty".