20809045 has 4 divisors (see below), whose sum is σ = 24970860. Its totient is φ = 16647232.

The previous prime is 20808989. The next prime is 20809049. The reversal of 20809045 is 54090802.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5489649 + 15319396 = 2343^2 + 3914^2 .

It is a cyclic number.

It is not a de Polignac number, because 20809045 - 2¹³ = 20800853 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20809049) 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 in 3 ways as a sum of consecutive naturals, for example, 2080900 + ... + 2080909.

It is an arithmetic number, because the mean of its divisors is an integer number (6242715).

Almost surely, 2^20809045 is an apocalyptic number.

It is an amenable number.

20809045 is a deficient number, since it is larger than the sum of its proper divisors (4161815).

20809045 is an equidigital number, since it uses as much as digits as its factorization.

20809045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4161814.

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 20809045 is about 4561.6932163397. The cubic root of 20809045 is about 275.0536314132.

Adding to 20809045 its reverse (54090802), we get a palindrome (74899847).

The spelling of 20809045 in words is "twenty million, eight hundred nine thousand, forty-five".