20871871 has 4 divisors (see below), whose sum is σ = 20883112. Its totient is φ = 20860632.

The previous prime is 20871863. The next prime is 20871881. The reversal of 20871871 is 17817802.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20871871 - 2³ = 20871863 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 (20871881) 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, 2100 + ... + 6793.

It is an arithmetic number, because the mean of its divisors is an integer number (5220778).

Almost surely, 2^20871871 is an apocalyptic number.

20871871 is a deficient number, since it is larger than the sum of its proper divisors (11241).

20871871 is an equidigital number, since it uses as much as digits as its factorization.

20871871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11240.

The product of its (nonzero) digits is 6272, while the sum is 34.

The square root of 20871871 is about 4568.5742852667. The cubic root of 20871871 is about 275.3301643284.

The spelling of 20871871 in words is "twenty million, eight hundred seventy-one thousand, eight hundred seventy-one".