21440500 has 48 divisors (see below), whose sum is σ = 47318544. Its totient is φ = 8486400.

The previous prime is 21440491. The next prime is 21440527. The reversal of 21440500 is 504412.

It can be written as a sum of positive squares in 8 ways, for example, as 13454224 + 7986276 = 3668^2 + 2826^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 68344 + ... + 68656.

It is an arithmetic number, because the mean of its divisors is an integer number (985803).

Almost surely, 2^21440500 is an apocalyptic number.

21440500 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 21440500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23659272).

21440500 is an abundant number, since it is smaller than the sum of its proper divisors (25878044).

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

21440500 is a wasteful number, since it uses less digits than its factorization.

21440500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 469 (or 457 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 16.

The square root of 21440500 is about 4630.3887525779. The cubic root of 21440500 is about 277.8081418659.

Adding to 21440500 its reverse (504412), we get a palindrome (21944912).

The spelling of 21440500 in words is "twenty-one million, four hundred forty thousand, five hundred".