21344440 has 32 divisors (see below), whose sum is σ = 51720480. Its totient is φ = 7880832.

The previous prime is 21344419. The next prime is 21344447. The reversal of 21344440 is 4444312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21344447) 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, 20004 + ... + 21043.

It is an arithmetic number, because the mean of its divisors is an integer number (1616265).

Almost surely, 2^21344440 is an apocalyptic number.

21344440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21344440 is an abundant number, since it is smaller than the sum of its proper divisors (30376040).

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

21344440 is a wasteful number, since it uses less digits than its factorization.

21344440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41071 (or 41067 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 22.

The square root of 21344440 is about 4620.0043290023. The cubic root of 21344440 is about 277.3926322184.

Adding to 21344440 its reverse (4444312), we get a palindrome (25788752).

The spelling of 21344440 in words is "twenty-one million, three hundred forty-four thousand, four hundred forty".