20809133 has 4 divisors (see below), whose sum is σ = 21371580. Its totient is φ = 20246688.

The previous prime is 20809121. The next prime is 20809141. The reversal of 20809133 is 33190802.

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 8684809 + 12124324 = 2947^2 + 3482^2 .

It is a cyclic number.

It is not a de Polignac number, because 20809133 - 2¹⁴ = 20792749 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20809163) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 281168 + ... + 281241.

It is an arithmetic number, because the mean of its divisors is an integer number (5342895).

Almost surely, 2^20809133 is an apocalyptic number.

It is an amenable number.

20809133 is a deficient number, since it is larger than the sum of its proper divisors (562447).

20809133 is an equidigital number, since it uses as much as digits as its factorization.

20809133 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562446.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 20809133 is about 4561.7028618708. The cubic root of 20809133 is about 275.0540191402.

Adding to 20809133 its reverse (33190802), we get a palindrome (53999935).

The spelling of 20809133 in words is "twenty million, eight hundred nine thousand, one hundred thirty-three".