20405425 has 6 divisors (see below), whose sum is σ = 25302758. Its totient is φ = 16324320.

The previous prime is 20405387. The next prime is 20405443. The reversal of 20405425 is 52450402.

It can be written as a sum of positive squares in 3 ways, for example, as 3041536 + 17363889 = 1744^2 + 4167^2 .

It is not a de Polignac number, because 20405425 - 2¹¹ = 20403377 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20405396 and 20405405.

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, 408084 + ... + 408133.

Almost surely, 2^20405425 is an apocalyptic number.

20405425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20405425 is a deficient number, since it is larger than the sum of its proper divisors (4897333).

20405425 is an equidigital number, since it uses as much as digits as its factorization.

20405425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816227 (or 816222 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 22.

The square root of 20405425 is about 4517.2364339273. The cubic root of 20405425 is about 273.2636604426.

Adding to 20405425 its reverse (52450402), we get a palindrome (72855827).

The spelling of 20405425 in words is "twenty million, four hundred five thousand, four hundred twenty-five".