21242575 has 6 divisors (see below), whose sum is σ = 26340824. Its totient is φ = 16994040.

The previous prime is 21242569. The next prime is 21242591. The reversal of 21242575 is 57524212.

It is not a de Polignac number, because 21242575 - 2⁹ = 21242063 is a prime.

It is a Duffinian number.

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 5 ways as a sum of consecutive naturals, for example, 424827 + ... + 424876.

Almost surely, 2^21242575 is an apocalyptic number.

21242575 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21242575 is a deficient number, since it is larger than the sum of its proper divisors (5098249).

21242575 is an equidigital number, since it uses as much as digits as its factorization.

21242575 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 849713 (or 849708 counting only the distinct ones).

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

The square root of 21242575 is about 4608.9668039594. The cubic root of 21242575 is about 276.9506487168.

Adding to 21242575 its reverse (57524212), we get a palindrome (78766787).

The spelling of 21242575 in words is "twenty-one million, two hundred forty-two thousand, five hundred seventy-five".