21120245 has 4 divisors (see below), whose sum is σ = 25344300. Its totient is φ = 16896192.

The previous prime is 21120223. The next prime is 21120251. The reversal of 21120245 is 54202112.

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 16630084 + 4490161 = 4078^2 + 2119^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120245 - 2²⁴ = 4343029 is a prime.

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 3 ways as a sum of consecutive naturals, for example, 2112020 + ... + 2112029.

It is an arithmetic number, because the mean of its divisors is an integer number (6336075).

Almost surely, 2^21120245 is an apocalyptic number.

It is an amenable number.

21120245 is a deficient number, since it is larger than the sum of its proper divisors (4224055).

21120245 is an equidigital number, since it uses as much as digits as its factorization.

21120245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4224054.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21120245 is about 4595.6767727942. The cubic root of 21120245 is about 276.4179980433.

Adding to 21120245 its reverse (54202112), we get a palindrome (75322357).

The spelling of 21120245 in words is "twenty-one million, one hundred twenty thousand, two hundred forty-five".