21730225 has 24 divisors (see below), whose sum is σ = 30355200. Its totient is φ = 15288000.

The previous prime is 21730169. The next prime is 21730249. The reversal of 21730225 is 52203712.

It is not a de Polignac number, because 21730225 - 2¹¹ = 21728177 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21730196 and 21730205.

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 23 ways as a sum of consecutive naturals, for example, 7251 + ... + 9799.

It is an arithmetic number, because the mean of its divisors is an integer number (1264800).

Almost surely, 2^21730225 is an apocalyptic number.

21730225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21730225 is a deficient number, since it is larger than the sum of its proper divisors (8624975).

21730225 is a wasteful number, since it uses less digits than its factorization.

21730225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2601 (or 2596 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21730225 is about 4661.5689418907. The cubic root of 21730225 is about 279.0538857820.

Adding to 21730225 its reverse (52203712), we get a palindrome (73933937).

The spelling of 21730225 in words is "twenty-one million, seven hundred thirty thousand, two hundred twenty-five".