21080440 has 32 divisors (see below), whose sum is σ = 48444480. Its totient is φ = 8252032.

The previous prime is 21080401. The next prime is 21080447. The reversal of 21080440 is 4408012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21080447) 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 7 ways as a sum of consecutive naturals, for example, 3727 + ... + 7486.

It is an arithmetic number, because the mean of its divisors is an integer number (1513890).

Almost surely, 2^21080440 is an apocalyptic number.

21080440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21080440 is an abundant number, since it is smaller than the sum of its proper divisors (27364040).

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

21080440 is a wasteful number, since it uses less digits than its factorization.

21080440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11271 (or 11267 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 19.

The square root of 21080440 is about 4591.3440298022. The cubic root of 21080440 is about 276.2442352557.

Adding to 21080440 its reverse (4408012), we get a palindrome (25488452).

The spelling of 21080440 in words is "twenty-one million, eighty thousand, four hundred forty".