21258845 has 4 divisors (see below), whose sum is σ = 25510620. Its totient is φ = 17007072.

The previous prime is 21258833. The next prime is 21258847. The reversal of 21258845 is 54885212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14092516 + 7166329 = 3754^2 + 2677^2 .

It is a cyclic number.

It is not a de Polignac number, because 21258845 - 2⁶ = 21258781 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21258847) 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 3 ways as a sum of consecutive naturals, for example, 2125880 + ... + 2125889.

It is an arithmetic number, because the mean of its divisors is an integer number (6377655).

Almost surely, 2^21258845 is an apocalyptic number.

It is an amenable number.

21258845 is a deficient number, since it is larger than the sum of its proper divisors (4251775).

21258845 is an equidigital number, since it uses as much as digits as its factorization.

21258845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4251774.

The product of its digits is 25600, while the sum is 35.

The square root of 21258845 is about 4610.7315037855. The cubic root of 21258845 is about 277.0213375284.

The spelling of 21258845 in words is "twenty-one million, two hundred fifty-eight thousand, eight hundred forty-five".