21440000 has 100 divisors (see below), whose sum is σ = 54329484. Its totient is φ = 8448000.

The previous prime is 21439997. The next prime is 21440017. The reversal of 21440000 is 4412.

It is a tau number, because it is divible by the number of its divisors (100).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 319967 + ... + 320033.

Almost surely, 2^21440000 is an apocalyptic number.

21440000 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 21440000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27164742).

21440000 is an abundant number, since it is smaller than the sum of its proper divisors (32889484).

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

21440000 is an frugal number, since it uses more digits than its factorization.

21440000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105 (or 74 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 21440000 is about 4630.3347611161. The cubic root of 21440000 is about 277.8059823213.

Adding to 21440000 its reverse (4412), we get a palindrome (21444412).

The spelling of 21440000 in words is "twenty-one million, four hundred forty thousand".