20561225 has 12 divisors (see below), whose sum is σ = 25785180. Its totient is φ = 16262400.

The previous prime is 20561221. The next prime is 20561237. The reversal of 20561225 is 52216502.

It can be written as a sum of positive squares in 6 ways, for example, as 22201 + 20539024 = 149^2 + 4532^2 .

It is not a de Polignac number, because 20561225 - 2² = 20561221 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20561225.

It is not an unprimeable number, because it can be changed into a prime (20561221) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2396 + ... + 6845.

It is an arithmetic number, because the mean of its divisors is an integer number (2148765).

Almost surely, 2^20561225 is an apocalyptic number.

20561225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20561225 is a deficient number, since it is larger than the sum of its proper divisors (5223955).

20561225 is an equidigital number, since it uses as much as digits as its factorization.

20561225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9340 (or 9335 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 20561225 is about 4534.4486985741. The cubic root of 20561225 is about 273.9573743342.

Adding to 20561225 its reverse (52216502), we get a palindrome (72777727).

The spelling of 20561225 in words is "twenty million, five hundred sixty-one thousand, two hundred twenty-five".