21978738545400 has 864 divisors, whose sum is σ = 92837305688400. Its totient is φ = 4618736640000.

The previous prime is 21978738545389. The next prime is 21978738545417. The reversal of 21978738545400 is 454583787912.

21978738545400 is a `hidden beast` number, since 2 + 1 + 9 + 7 + 8 + 7 + 3 + 85 + 4 + 540 + 0 = 666.

It is a super-2 number, since 2×21978738545400² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 215 ways as a sum of consecutive naturals, for example, 287758416 + ... + 287834784.

Almost surely, 2^{21978738545400} is an apocalyptic number.

21978738545400 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 21978738545400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46418652844200).

21978738545400 is an abundant number, since it is smaller than the sum of its proper divisors (70858567143000).

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

21978738545400 is a wasteful number, since it uses less digits than its factorization.

21978738545400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76669 (or 76650 counting only the distinct ones).

The product of its (nonzero) digits is 67737600, while the sum is 63.

The spelling of 21978738545400 in words is "twenty-one trillion, nine hundred seventy-eight billion, seven hundred thirty-eight million, five hundred forty-five thousand, four hundred".