21021478646400 has 768 divisors, whose sum is σ = 79749181440000. Its totient is φ = 5402034892800.

The previous prime is 21021478646387. The next prime is 21021478646401. The reversal of 21021478646400 is 464687412012.

21021478646400 is a `hidden beast` number, since 2 + 102 + 1 + 4 + 7 + 86 + 464 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21021478646401) by changing a digit.

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 95 ways as a sum of consecutive naturals, for example, 640121181 + ... + 640154019.

It is an arithmetic number, because the mean of its divisors is an integer number (103840080000).

Almost surely, 2^{21021478646400} is an apocalyptic number.

21021478646400 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 21021478646400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39874590720000).

21021478646400 is an abundant number, since it is smaller than the sum of its proper divisors (58727702793600).

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

21021478646400 is a wasteful number, since it uses less digits than its factorization.

21021478646400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33142 (or 33119 counting only the distinct ones).

The product of its (nonzero) digits is 516096, while the sum is 45.

The spelling of 21021478646400 in words is "twenty-one trillion, twenty-one billion, four hundred seventy-eight million, six hundred forty-six thousand, four hundred".