21221551026560 has 128 divisors (see below), whose sum is σ = 53537444575200. Its totient is φ = 8021592539136.

The previous prime is 21221551026553. The next prime is 21221551026581. The reversal of 21221551026560 is 6562015512212.

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

It is a Harshad number since it is a multiple of its sum of digits (38).

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, 2629544 + ... + 7025496.

Almost surely, 2^{21221551026560} is an apocalyptic number.

21221551026560 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 21221551026560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26768722287600).

21221551026560 is an abundant number, since it is smaller than the sum of its proper divisors (32315893548640).

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

21221551026560 is a wasteful number, since it uses less digits than its factorization.

21221551026560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4396388 (or 4396376 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 38.

Adding to 21221551026560 its reverse (6562015512212), we get a palindrome (27783566538772).

The spelling of 21221551026560 in words is "twenty-one trillion, two hundred twenty-one billion, five hundred fifty-one million, twenty-six thousand, five hundred sixty".