21355505460520 has 512 divisors, whose sum is σ = 65595499315200. Its totient is φ = 6051601612800.

The previous prime is 21355505460463. The next prime is 21355505460521. The reversal of 21355505460520 is 2506450555312.

It is a super-2 number, since 2×21355505460520² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21355505460521) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 913827396 + ... + 913850764.

It is an arithmetic number, because the mean of its divisors is an integer number (128116209600).

Almost surely, 2^{21355505460520} is an apocalyptic number.

21355505460520 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 21355505460520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32797749657600).

21355505460520 is an abundant number, since it is smaller than the sum of its proper divisors (44239993854680).

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

21355505460520 is a wasteful number, since it uses less digits than its factorization.

21355505460520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24009 (or 24005 counting only the distinct ones).

The product of its (nonzero) digits is 900000, while the sum is 43.

The spelling of 21355505460520 in words is "twenty-one trillion, three hundred fifty-five billion, five hundred five million, four hundred sixty thousand, five hundred twenty".