21555956822400 has 3072 divisors, whose sum is σ = 108194675097600. Its totient is φ = 4045875609600.

The previous prime is 21555956822371. The next prime is 21555956822423. The reversal of 21555956822400 is 422865955512.

It is a happy number.

21555956822400 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 59 + 568 + 2 + 24 + 0 + 0 = 666.

It is a super-3 number, since 3×21555956822400³ (a number of 41 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 4064858149 + ... + 4064863451.

It is an arithmetic number, because the mean of its divisors is an integer number (35219620800).

Almost surely, 2^{21555956822400} is an apocalyptic number.

21555956822400 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 21555956822400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (54097337548800).

21555956822400 is an abundant number, since it is smaller than the sum of its proper divisors (86638718275200).

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

21555956822400 is a wasteful number, since it uses less digits than its factorization.

21555956822400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5414 (or 5391 counting only the distinct ones).

The product of its (nonzero) digits is 8640000, while the sum is 54.

The spelling of 21555956822400 in words is "twenty-one trillion, five hundred fifty-five billion, nine hundred fifty-six million, eight hundred twenty-two thousand, four hundred".