21561170831200 has 1152 divisors, whose sum is σ = 74608224768000. Its totient is φ = 5859844300800.

The previous prime is 21561170831171. The next prime is 21561170831269. The reversal of 21561170831200 is 213807116512.

21561170831200 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×21561170831200² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21561170831200.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 5766558931 + ... + 5766562669.

It is an arithmetic number, because the mean of its divisors is an integer number (64764084000).

Almost surely, 2^{21561170831200} is an apocalyptic number.

21561170831200 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 21561170831200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37304112384000).

21561170831200 is an abundant number, since it is smaller than the sum of its proper divisors (53047053936800).

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

21561170831200 is a wasteful number, since it uses less digits than its factorization.

21561170831200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4188 (or 4175 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 37.

Adding to 21561170831200 its reverse (213807116512), we get a palindrome (21774977947712).

The spelling of 21561170831200 in words is "twenty-one trillion, five hundred sixty-one billion, one hundred seventy million, eight hundred thirty-one thousand, two hundred".