20809671 has 4 divisors (see below), whose sum is σ = 27746232. Its totient is φ = 13873112.

The previous prime is 20809669. The next prime is 20809699. The reversal of 20809671 is 17690802.

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

It is a cyclic number.

It is not a de Polignac number, because 20809671 - 2¹ = 20809669 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20809631) 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, 3468276 + ... + 3468281.

It is an arithmetic number, because the mean of its divisors is an integer number (6936558).

Almost surely, 2^20809671 is an apocalyptic number.

20809671 is a deficient number, since it is larger than the sum of its proper divisors (6936561).

20809671 is an equidigital number, since it uses as much as digits as its factorization.

20809671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6936560.

The product of its (nonzero) digits is 6048, while the sum is 33.

The square root of 20809671 is about 4561.7618306966. The cubic root of 20809671 is about 275.0563895383.

The spelling of 20809671 in words is "twenty million, eight hundred nine thousand, six hundred seventy-one".