21024440 has 32 divisors (see below), whose sum is σ = 47537280. Its totient is φ = 8368512.

The previous prime is 21024433. The next prime is 21024457. The reversal of 21024440 is 4442012.

It is a congruent number.

It is an unprimeable number.

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, 7742 + ... + 10098.

It is an arithmetic number, because the mean of its divisors is an integer number (1485540).

Almost surely, 2^21024440 is an apocalyptic number.

21024440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21024440 is an abundant number, since it is smaller than the sum of its proper divisors (26512840).

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

21024440 is a wasteful number, since it uses less digits than its factorization.

21024440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2591 (or 2587 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 21024440 is about 4585.2415421655. The cubic root of 21024440 is about 275.9994048856. Note that the first 3 decimals are identical.

Adding to 21024440 its reverse (4442012), we get a palindrome (25466452).

The spelling of 21024440 in words is "twenty-one million, twenty-four thousand, four hundred forty".