21305342520 has 1280 divisors, whose sum is σ = 96347750400. Its totient is φ = 4092042240.

The previous prime is 21305342491. The next prime is 21305342603. The reversal of 21305342520 is 2524350312.

It is a happy number.

21305342520 is a `hidden beast` number, since 2 + 130 + 5 + 3 + 4 + 2 + 520 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 319 ways as a sum of consecutive naturals, for example, 269687841 + ... + 269687919.

It is an arithmetic number, because the mean of its divisors is an integer number (75271680).

Almost surely, 2^21305342520 is an apocalyptic number.

21305342520 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 21305342520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48173875200).

21305342520 is an abundant number, since it is smaller than the sum of its proper divisors (75042407880).

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

21305342520 is a wasteful number, since it uses less digits than its factorization.

21305342520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 190 (or 177 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 27.

Adding to 21305342520 its reverse (2524350312), we get a palindrome (23829692832).

The spelling of 21305342520 in words is "twenty-one billion, three hundred five million, three hundred forty-two thousand, five hundred twenty".