21778200 has 192 divisors, whose sum is σ = 77748000. Its totient is φ = 5598720.

The previous prime is 21778193. The next prime is 21778201. The reversal of 21778200 is 287712.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21778201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 199746 + ... + 199854.

Almost surely, 2^21778200 is an apocalyptic number.

21778200 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 21778200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38874000).

21778200 is an abundant number, since it is smaller than the sum of its proper divisors (55969800).

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

21778200 is a wasteful number, since it uses less digits than its factorization.

21778200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171 (or 156 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 27.

The square root of 21778200 is about 4666.7119045426. The cubic root of 21778200 is about 279.2590956537.

The spelling of 21778200 in words is "twenty-one million, seven hundred seventy-eight thousand, two hundred".