20805425 has 6 divisors (see below), whose sum is σ = 25798758. Its totient is φ = 16644320.

The previous prime is 20805419. The next prime is 20805427. The reversal of 20805425 is 52450802.

It can be written as a sum of positive squares in 3 ways, for example, as 2704 + 20802721 = 52^2 + 4561^2 .

It is not a de Polignac number, because 20805425 - 2¹⁰ = 20804401 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20805394 and 20805403.

It is not an unprimeable number, because it can be changed into a prime (20805427) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 416084 + ... + 416133.

It is an arithmetic number, because the mean of its divisors is an integer number (4299793).

Almost surely, 2^20805425 is an apocalyptic number.

20805425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20805425 is a deficient number, since it is larger than the sum of its proper divisors (4993333).

20805425 is an equidigital number, since it uses as much as digits as its factorization.

20805425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832227 (or 832222 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 26.

The square root of 20805425 is about 4561.2964165904. The cubic root of 20805425 is about 275.0376807871.

The spelling of 20805425 in words is "twenty million, eight hundred five thousand, four hundred twenty-five".