21904000 has 96 divisors (see below), whose sum is σ = 55970460. Its totient is φ = 8524800.

The previous prime is 21903991. The next prime is 21904031. The reversal of 21904000 is 40912.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 6 ways, for example, as 7706176 + 14197824 = 2776^2 + 3768^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 591982 + ... + 592018.

Almost surely, 2^21904000 is an apocalyptic number.

21904000 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 21904000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27985230).

21904000 is an abundant number, since it is smaller than the sum of its proper divisors (34066460).

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

21904000 is an frugal number, since it uses more digits than its factorization.

21904000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103 (or 44 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21904000 is about 4680.1709370492. The cubic root of 21904000 is about 279.7957694388.

Adding to 21904000 its reverse (40912), we get a palindrome (21944912).

The spelling of 21904000 in words is "twenty-one million, nine hundred four thousand".