21545215200 has 216 divisors, whose sum is σ = 80443320048. Its totient is φ = 5407395840.

The previous prime is 21545215163. The next prime is 21545215207. The reversal of 21545215200 is 251254512.

21545215200 is a `hidden beast` number, since 2 + 1 + 5 + 452 + 1 + 5 + 200 = 666.

It is a super-2 number, since 2×21545215200² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21545215207) by changing a digit.

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 35 ways as a sum of consecutive naturals, for example, 34389 + ... + 210411.

It is an arithmetic number, because the mean of its divisors is an integer number (372422778).

Almost surely, 2^21545215200 is an apocalyptic number.

21545215200 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 21545215200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40221660024).

21545215200 is an abundant number, since it is smaller than the sum of its proper divisors (58898104848).

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

21545215200 is a wasteful number, since it uses less digits than its factorization.

21545215200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176066 (or 176050 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 27.

Adding to 21545215200 its reverse (251254512), we get a palindrome (21796469712).

The spelling of 21545215200 in words is "twenty-one billion, five hundred forty-five million, two hundred fifteen thousand, two hundred".