21500551122420 has 192 divisors, whose sum is σ = 63091757998080. Its totient is φ = 5460412953600.

The previous prime is 21500551122367. The next prime is 21500551122503. The reversal of 21500551122420 is 2422115500512.

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

It is a congruent number.

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, 601715955 + ... + 601751685.

It is an arithmetic number, because the mean of its divisors is an integer number (328602906240).

Almost surely, 2^{21500551122420} is an apocalyptic number.

21500551122420 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 21500551122420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31545878999040).

21500551122420 is an abundant number, since it is smaller than the sum of its proper divisors (41591206875660).

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

21500551122420 is a wasteful number, since it uses less digits than its factorization.

21500551122420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37646 (or 37644 counting only the distinct ones).

The product of its (nonzero) digits is 8000, while the sum is 30.

Adding to 21500551122420 its reverse (2422115500512), we get a palindrome (23922666622932).

The spelling of 21500551122420 in words is "twenty-one trillion, five hundred billion, five hundred fifty-one million, one hundred twenty-two thousand, four hundred twenty".