21131711 has 2 divisors, whose sum is σ = 21131712. Its totient is φ = 21131710.

The previous prime is 21131707. The next prime is 21131713. The reversal of 21131711 is 11713112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21131711 - 2² = 21131707 is a prime.

Together with 21131713, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21131711.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21131713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565855 + 10565856.

It is an arithmetic number, because the mean of its divisors is an integer number (10565856).

Almost surely, 2^21131711 is an apocalyptic number.

21131711 is a deficient number, since it is larger than the sum of its proper divisors (1).

21131711 is an equidigital number, since it uses as much as digits as its factorization.

21131711 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42, while the sum is 17.

The square root of 21131711 is about 4596.9240802954. The cubic root of 21131711 is about 276.4680106480.

Adding to 21131711 its reverse (11713112), we get a palindrome (32844823).

The spelling of 21131711 in words is "twenty-one million, one hundred thirty-one thousand, seven hundred eleven".