20523809 has 2 divisors, whose sum is σ = 20523810. Its totient is φ = 20523808.

The previous prime is 20523791. The next prime is 20523817. The reversal of 20523809 is 90832502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20502784 + 21025 = 4528^2 + 145^2 .

It is a cyclic number.

It is not a de Polignac number, because 20523809 - 2¹² = 20519713 is a prime.

It is not a weakly prime, because it can be changed into another prime (20523859) 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, 10261904 + 10261905.

It is an arithmetic number, because the mean of its divisors is an integer number (10261905).

Almost surely, 2^20523809 is an apocalyptic number.

It is an amenable number.

20523809 is a deficient number, since it is larger than the sum of its proper divisors (1).

20523809 is an equidigital number, since it uses as much as digits as its factorization.

20523809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 20523809 is about 4530.3210702995. The cubic root of 20523809 is about 273.7910967400.

The spelling of 20523809 in words is "twenty million, five hundred twenty-three thousand, eight hundred nine".