21442205 has 4 divisors (see below), whose sum is σ = 25730652. Its totient is φ = 17153760.

The previous prime is 21442163. The next prime is 21442229. The reversal of 21442205 is 50224412.

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 6240004 + 15202201 = 2498^2 + 3899^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21442205 is a prime.

It is a Duffinian number.

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, 2144216 + ... + 2144225.

It is an arithmetic number, because the mean of its divisors is an integer number (6432663).

Almost surely, 2^21442205 is an apocalyptic number.

It is an amenable number.

21442205 is a deficient number, since it is larger than the sum of its proper divisors (4288447).

21442205 is an equidigital number, since it uses as much as digits as its factorization.

21442205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4288446.

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 21442205 is about 4630.5728587293. The cubic root of 21442205 is about 277.8155056607.

Adding to 21442205 its reverse (50224412), we get a palindrome (71666617).

The spelling of 21442205 in words is "twenty-one million, four hundred forty-two thousand, two hundred five".