21272245 has 4 divisors (see below), whose sum is σ = 25526700. Its totient is φ = 17017792.

The previous prime is 21272213. The next prime is 21272269. The reversal of 21272245 is 54227212.

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 2140369 + 19131876 = 1463^2 + 4374^2 .

It is a cyclic number.

It is not a de Polignac number, because 21272245 - 2⁵ = 21272213 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2127220 + ... + 2127229.

It is an arithmetic number, because the mean of its divisors is an integer number (6381675).

Almost surely, 2^21272245 is an apocalyptic number.

It is an amenable number.

21272245 is a deficient number, since it is larger than the sum of its proper divisors (4254455).

21272245 is an equidigital number, since it uses as much as digits as its factorization.

21272245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4254454.

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

The square root of 21272245 is about 4612.1844065475. The cubic root of 21272245 is about 277.0795298754.

Adding to 21272245 its reverse (54227212), we get a palindrome (75499457).

The spelling of 21272245 in words is "twenty-one million, two hundred seventy-two thousand, two hundred forty-five".