25205209 has 2 divisors, whose sum is σ = 25205210. Its totient is φ = 25205208.

The previous prime is 25205197. The next prime is 25205239. The reversal of 25205209 is 90250252.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25000000 + 205209 = 5000^2 + 453^2 .

It is a cyclic number.

It is not a de Polignac number, because 25205209 - 2¹⁹ = 24680921 is a prime.

It is not a weakly prime, because it can be changed into another prime (25205239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12602604 + 12602605.

It is an arithmetic number, because the mean of its divisors is an integer number (12602605).

Almost surely, 2^25205209 is an apocalyptic number.

It is an amenable number.

25205209 is a deficient number, since it is larger than the sum of its proper divisors (1).

25205209 is an equidigital number, since it uses as much as digits as its factorization.

25205209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 25205209 is about 5020.4789612148. The cubic root of 25205209 is about 293.1996410680.

It can be divided in two parts, 25 and 205209, that multiplied together give a square (5130225 = 2265²).

The spelling of 25205209 in words is "twenty-five million, two hundred five thousand, two hundred nine".