2505809 has 2 divisors, whose sum is σ = 2505810.
Its totient is φ = 2505808.
The previous prime is 2505793. The next prime is 2505829. The reversal of 2505809 is 9085052.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 2496400 + 9409 = 1580^2 + 97^2
It is a cyclic number.
It is not a de Polignac number, because 2505809 - 24 = 2505793 is a prime.
It is a Sophie Germain prime.
It is a Curzon number.
It is not a weakly prime, because it can be changed into another prime (2505829) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1252904 + 1252905.
It is an arithmetic number, because the mean of its divisors is an integer number (1252905).
22505809 is an apocalyptic number.
It is an amenable number.
2505809 is a deficient number, since it is larger than the sum of its proper divisors (1).
2505809 is an equidigital number, since it uses as much as digits as its factorization.
2505809 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 3600, while the sum is 29.
The square root of 2505809 is about 1582.9747313207.
The cubic root of 2505809 is about 135.8259198617.
The spelling of 2505809 in words is "two million, five hundred five thousand, eight hundred nine".