20109871 has 2 divisors, whose sum is σ = 20109872. Its totient is φ = 20109870.

The previous prime is 20109863. The next prime is 20109877. The reversal of 20109871 is 17890102.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20109871 - 2³ = 20109863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20109877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10054935 + 10054936.

It is an arithmetic number, because the mean of its divisors is an integer number (10054936).

Almost surely, 2^20109871 is an apocalyptic number.

20109871 is a deficient number, since it is larger than the sum of its proper divisors (1).

20109871 is an equidigital number, since it uses as much as digits as its factorization.

20109871 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 20109871 is about 4484.4030817936. The cubic root of 20109871 is about 271.9379138499.

Adding to 20109871 its reverse (17890102), we get a palindrome (37999973).

It can be divided in two parts, 2010 and 9871, that added together give a square (11881 = 109²).

The spelling of 20109871 in words is "twenty million, one hundred nine thousand, eight hundred seventy-one".