21551200000 has 432 divisors, whose sum is σ = 61316075520. Its totient is φ = 7488000000.

The previous prime is 21551199997. The next prime is 21551200007. The reversal of 21551200000 is 215512.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21551200007) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 272799961 + ... + 272800039.

It is an arithmetic number, because the mean of its divisors is an integer number (141935360).

Almost surely, 2^21551200000 is an apocalyptic number.

21551200000 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 21551200000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30658037760).

21551200000 is an abundant number, since it is smaller than the sum of its proper divisors (39764875520).

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

21551200000 is an frugal number, since it uses more digits than its factorization.

21551200000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162 (or 128 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 16.

Adding to 21551200000 its reverse (215512), we get a palindrome (21551415512).

21551200000 divided by its reverse (215512) gives a 5-th power (100000 = 10⁵).

It can be divided in two parts, 215 and 51200000, that added together give a palindrome (51200215).

The spelling of 21551200000 in words is "twenty-one billion, five hundred fifty-one million, two hundred thousand".