21143225 has 6 divisors (see below), whose sum is σ = 26217630. Its totient is φ = 16914560.

The previous prime is 21143207. The next prime is 21143251. The reversal of 21143225 is 52234112.

It can be written as a sum of positive squares in 3 ways, for example, as 10816 + 21132409 = 104^2 + 4597^2 .

It is not a de Polignac number, because 21143225 - 2⁸ = 21142969 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21143197 and 21143206.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 422840 + ... + 422889.

It is an arithmetic number, because the mean of its divisors is an integer number (4369605).

Almost surely, 2^21143225 is an apocalyptic number.

21143225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21143225 is a deficient number, since it is larger than the sum of its proper divisors (5074405).

21143225 is an equidigital number, since it uses as much as digits as its factorization.

21143225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 845739 (or 845734 counting only the distinct ones).

The product of its digits is 480, while the sum is 20.

The square root of 21143225 is about 4598.1762689136. The cubic root of 21143225 is about 276.5182144183.

Adding to 21143225 its reverse (52234112), we get a palindrome (73377337).

The spelling of 21143225 in words is "twenty-one million, one hundred forty-three thousand, two hundred twenty-five".