21355233280 has 68 divisors (see below), whose sum is σ = 51252955272. Its totient is φ = 8541962240.

The previous prime is 21355233259. The next prime is 21355233323. The reversal of 21355233280 is 8233255312.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 295095 + ... + 360265.

Almost surely, 2^21355233280 is an apocalyptic number.

21355233280 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 21355233280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25626477636).

21355233280 is an abundant number, since it is smaller than the sum of its proper divisors (29897721992).

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

21355233280 is an frugal number, since it uses more digits than its factorization.

21355233280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65208 (or 65178 counting only the distinct ones).

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

Adding to 21355233280 its reverse (8233255312), we get a palindrome (29588488592).

The spelling of 21355233280 in words is "twenty-one billion, three hundred fifty-five million, two hundred thirty-three thousand, two hundred eighty".