20405225 has 6 divisors (see below), whose sum is σ = 25302510. Its totient is φ = 16324160.

The previous prime is 20405213. The next prime is 20405233. The reversal of 20405225 is 52250402.

It can be written as a sum of positive squares in 3 ways, for example, as 1936 + 20403289 = 44^2 + 4517^2 .

It is a de Polignac number, because none of the positive numbers 2^k-20405225 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20405197 and 20405206.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 408080 + ... + 408129.

It is an arithmetic number, because the mean of its divisors is an integer number (4217085).

Almost surely, 2^20405225 is an apocalyptic number.

20405225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20405225 is a deficient number, since it is larger than the sum of its proper divisors (4897285).

20405225 is an equidigital number, since it uses as much as digits as its factorization.

20405225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816219 (or 816214 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 20.

The square root of 20405225 is about 4517.2142964442. The cubic root of 20405225 is about 273.2627676586.

Adding to 20405225 its reverse (52250402), we get a palindrome (72655627).

The spelling of 20405225 in words is "twenty million, four hundred five thousand, two hundred twenty-five".