21075449 has 4 divisors (see below), whose sum is σ = 21432720. Its totient is φ = 20718180.

The previous prime is 21075437. The next prime is 21075451. The reversal of 21075449 is 94457012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21075449 - 2⁴ = 21075433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21075419) 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 3 ways as a sum of consecutive naturals, for example, 178547 + ... + 178664.

It is an arithmetic number, because the mean of its divisors is an integer number (5358180).

Almost surely, 2^21075449 is an apocalyptic number.

It is an amenable number.

21075449 is a deficient number, since it is larger than the sum of its proper divisors (357271).

21075449 is an equidigital number, since it uses as much as digits as its factorization.

21075449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 357270.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21075449 is about 4590.8004748627. The cubic root of 21075449 is about 276.2224323616. Note that the first 3 decimals are identical.

The spelling of 21075449 in words is "twenty-one million, seventy-five thousand, four hundred forty-nine".