21440575 has 24 divisors (see below), whose sum is σ = 29421728. Its totient is φ = 15396480.

The previous prime is 21440539. The next prime is 21440579. The reversal of 21440575 is 57504412.

It is a de Polignac number, because none of the positive numbers 2^k-21440575 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21440579) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11134 + ... + 12916.

Almost surely, 2^21440575 is an apocalyptic number.

21440575 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21440575 is a deficient number, since it is larger than the sum of its proper divisors (7981153).

21440575 is a wasteful number, since it uses less digits than its factorization.

21440575 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1843 (or 1838 counting only the distinct ones).

The product of its (nonzero) digits is 5600, while the sum is 28.

The square root of 21440575 is about 4630.3968512429. The cubic root of 21440575 is about 277.8084657947.

Adding to 21440575 its reverse (57504412), we get a palindrome (78944987).

The spelling of 21440575 in words is "twenty-one million, four hundred forty thousand, five hundred seventy-five".