20871881 has 2 divisors, whose sum is σ = 20871882. Its totient is φ = 20871880.

The previous prime is 20871863. The next prime is 20871883. The reversal of 20871881 is 18817802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20106256 + 765625 = 4484^2 + 875^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20871881 is a prime.

It is a super-2 number, since 2×20871881² = 871270832956322, which contains 22 as substring.

Together with 20871883, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20871883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10435940 + 10435941.

It is an arithmetic number, because the mean of its divisors is an integer number (10435941).

Almost surely, 2^20871881 is an apocalyptic number.

It is an amenable number.

20871881 is a deficient number, since it is larger than the sum of its proper divisors (1).

20871881 is an equidigital number, since it uses as much as digits as its factorization.

20871881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7168, while the sum is 35.

The square root of 20871881 is about 4568.5753796999. The cubic root of 20871881 is about 275.3302082999.

The spelling of 20871881 in words is "twenty million, eight hundred seventy-one thousand, eight hundred eighty-one".