25121809 has 2 divisors, whose sum is σ = 25121810. Its totient is φ = 25121808.

The previous prime is 25121783. The next prime is 25121867. The reversal of 25121809 is 90812152.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21827584 + 3294225 = 4672^2 + 1815^2 .

It is a cyclic number.

It is not a de Polignac number, because 25121809 - 2¹⁵ = 25089041 is a prime.

It is a super-2 number, since 2×25121809² = 1262210574864962, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (25121209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12560904 + 12560905.

It is an arithmetic number, because the mean of its divisors is an integer number (12560905).

Almost surely, 2^25121809 is an apocalyptic number.

It is an amenable number.

25121809 is a deficient number, since it is larger than the sum of its proper divisors (1).

25121809 is an equidigital number, since it uses as much as digits as its factorization.

25121809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 25121809 is about 5012.1660986045. The cubic root of 25121809 is about 292.8759001838.

The spelling of 25121809 in words is "twenty-five million, one hundred twenty-one thousand, eight hundred nine".