20808971 has 4 divisors (see below), whose sum is σ = 21904200. Its totient is φ = 19713744.

The previous prime is 20808943. The next prime is 20808989. The reversal of 20808971 is 17980802.

It is a happy number.

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 20808971 - 2¹⁰ = 20807947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20808071) 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, 547586 + ... + 547623.

It is an arithmetic number, because the mean of its divisors is an integer number (5476050).

Almost surely, 2^20808971 is an apocalyptic number.

20808971 is a deficient number, since it is larger than the sum of its proper divisors (1095229).

20808971 is a wasteful number, since it uses less digits than its factorization.

20808971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1095228.

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 20808971 is about 4561.6851053092. The cubic root of 20808971 is about 275.0533053692.

The spelling of 20808971 in words is "twenty million, eight hundred eight thousand, nine hundred seventy-one".