21305335620 has 192 divisors, whose sum is σ = 63077253120. Its totient is φ = 5362655232.

The previous prime is 21305335619. The next prime is 21305335637. The reversal of 21305335620 is 2653350312.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 44478541 + ... + 44479019.

It is an arithmetic number, because the mean of its divisors is an integer number (328527360).

Almost surely, 2^21305335620 is an apocalyptic number.

21305335620 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 21305335620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31538626560).

21305335620 is an abundant number, since it is smaller than the sum of its proper divisors (41771917500).

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

21305335620 is a wasteful number, since it uses less digits than its factorization.

21305335620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 874 (or 872 counting only the distinct ones).

The product of its (nonzero) digits is 16200, while the sum is 30.

Adding to 21305335620 its reverse (2653350312), we get a palindrome (23958685932).

The spelling of 21305335620 in words is "twenty-one billion, three hundred five million, three hundred thirty-five thousand, six hundred twenty".