21789000 has 160 divisors (see below), whose sum is σ = 76447800. Its totient is φ = 5788800.

The previous prime is 21788983. The next prime is 21789007. The reversal of 21789000 is 98712.

It can be written as a sum of positive squares in 4 ways, for example, as 2022084 + 19766916 = 1422^2 + 4446^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

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

It is a zygodrome in base 3 and base 9.

It is not an unprimeable number, because it can be changed into a prime (21789007) 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 39 ways as a sum of consecutive naturals, for example, 80866 + ... + 81134.

Almost surely, 2^21789000 is an apocalyptic number.

21789000 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 21789000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38223900).

21789000 is an abundant number, since it is smaller than the sum of its proper divisors (54658800).

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

21789000 is a wasteful number, since it uses less digits than its factorization.

21789000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 302 (or 279 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 21789000 is about 4667.8688927604. The cubic root of 21789000 is about 279.3052503683.

The spelling of 21789000 in words is "twenty-one million, seven hundred eighty-nine thousand".