21580000 has 120 divisors (see below), whose sum is σ = 57862728. Its totient is φ = 7872000.

The previous prime is 21579989. The next prime is 21580007. The reversal of 21580000 is 8512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21580007) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 259959 + ... + 260041.

Almost surely, 2^21580000 is an apocalyptic number.

21580000 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 21580000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28931364).

21580000 is an abundant number, since it is smaller than the sum of its proper divisors (36282728).

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

21580000 is an equidigital number, since it uses as much as digits as its factorization.

21580000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126 (or 103 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21580000 is about 4645.4278597348. The cubic root of 21580000 is about 278.4093481249.

Adding to 21580000 its reverse (8512), we get a palindrome (21588512).

The spelling of 21580000 in words is "twenty-one million, five hundred eighty thousand".