20804081 has 4 divisors (see below), whose sum is σ = 21010164. Its totient is φ = 20598000.

The previous prime is 20804059. The next prime is 20804087. The reversal of 20804081 is 18040802.

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 19722481 + 1081600 = 4441^2 + 1040^2 .

It is a cyclic number.

It is not a de Polignac number, because 20804081 - 2²² = 16609777 is a prime.

It is a super-2 number, since 2×20804081² = 865619572509122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20804087) 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, 102890 + ... + 103091.

It is an arithmetic number, because the mean of its divisors is an integer number (5252541).

Almost surely, 2^20804081 is an apocalyptic number.

It is an amenable number.

20804081 is a deficient number, since it is larger than the sum of its proper divisors (206083).

20804081 is a wasteful number, since it uses less digits than its factorization.

20804081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206082.

The product of its (nonzero) digits is 512, while the sum is 23.

The square root of 20804081 is about 4561.1490876752. The cubic root of 20804081 is about 275.0317583157.

Adding to 20804081 its reverse (18040802), we get a palindrome (38844883).

The spelling of 20804081 in words is "twenty million, eight hundred four thousand, eighty-one".