20145809 has 2 divisors, whose sum is σ = 20145810. Its totient is φ = 20145808.

The previous prime is 20145793. The next prime is 20145821. The reversal of 20145809 is 90854102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14250625 + 5895184 = 3775^2 + 2428^2 .

It is a cyclic number.

It is not a de Polignac number, because 20145809 - 2⁴ = 20145793 is a prime.

It is not a weakly prime, because it can be changed into another prime (20145859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10072904 + 10072905.

It is an arithmetic number, because the mean of its divisors is an integer number (10072905).

Almost surely, 2^20145809 is an apocalyptic number.

It is an amenable number.

20145809 is a deficient number, since it is larger than the sum of its proper divisors (1).

20145809 is an equidigital number, since it uses as much as digits as its factorization.

20145809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 20145809 is about 4488.4082924796. The cubic root of 20145809 is about 272.0998092835.

The spelling of 20145809 in words is "twenty million, one hundred forty-five thousand, eight hundred nine".