21345225 has 24 divisors (see below), whose sum is σ = 38500512. Its totient is φ = 10348800.

The previous prime is 21345223. The next prime is 21345229. The reversal of 21345225 is 52254312.

It is not a de Polignac number, because 21345225 - 2¹ = 21345223 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21345195 and 21345204.

It is not an unprimeable number, because it can be changed into a prime (21345223) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 12112 + ... + 13761.

It is an arithmetic number, because the mean of its divisors is an integer number (1604188).

Almost surely, 2^21345225 is an apocalyptic number.

21345225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21345225 is a deficient number, since it is larger than the sum of its proper divisors (17155287).

21345225 is a wasteful number, since it uses less digits than its factorization.

21345225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25897 (or 25892 counting only the distinct ones).

The product of its digits is 2400, while the sum is 24.

The square root of 21345225 is about 4620.0892848515. The cubic root of 21345225 is about 277.3960328003.

Adding to 21345225 its reverse (52254312), we get a palindrome (73599537).

The spelling of 21345225 in words is "twenty-one million, three hundred forty-five thousand, two hundred twenty-five".