21355012320640 has 128 divisors (see below), whose sum is σ = 52329518730720. Its totient is φ = 8328480276480.

The previous prime is 21355012320637. The next prime is 21355012320659. The reversal of 21355012320640 is 4602321055312.

It is a tau number, because it is divible by the number of its divisors (128).

It is a junction number, because it is equal to n+sod(n) for n = 21355012320596 and 21355012320605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42072847 + ... + 42577393.

Almost surely, 2^{21355012320640} is an apocalyptic number.

21355012320640 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 21355012320640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26164759365360).

21355012320640 is an abundant number, since it is smaller than the sum of its proper divisors (30974506410080).

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

21355012320640 is a wasteful number, since it uses less digits than its factorization.

21355012320640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506220 (or 506208 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 34.

Adding to 21355012320640 its reverse (4602321055312), we get a palindrome (25957333375952).

The spelling of 21355012320640 in words is "twenty-one trillion, three hundred fifty-five billion, twelve million, three hundred twenty thousand, six hundred forty".