21242275 has 6 divisors (see below), whose sum is σ = 26340452. Its totient is φ = 16993800.

The previous prime is 21242237. The next prime is 21242339. The reversal of 21242275 is 57224212.

It is not a de Polignac number, because 21242275 - 2⁹ = 21241763 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25), and also a Moran number because the ratio is a prime number: 849691 = 21242275 / (2 + 1 + 2 + 4 + 2 + 2 + 7 + 5).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 424821 + ... + 424870.

Almost surely, 2^21242275 is an apocalyptic number.

21242275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21242275 is a deficient number, since it is larger than the sum of its proper divisors (5098177).

21242275 is an equidigital number, since it uses as much as digits as its factorization.

21242275 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 849701 (or 849696 counting only the distinct ones).

The product of its digits is 2240, while the sum is 25.

The square root of 21242275 is about 4608.9342585895. The cubic root of 21242275 is about 276.9493449580.

Adding to 21242275 its reverse (57224212), we get a palindrome (78466487).

The spelling of 21242275 in words is "twenty-one million, two hundred forty-two thousand, two hundred seventy-five".