21171671 has 2 divisors, whose sum is σ = 21171672. Its totient is φ = 21171670.

The previous prime is 21171649. The next prime is 21171673. The reversal of 21171671 is 17617112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21171671 - 2¹⁰ = 21170647 is a prime.

Together with 21171673, 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 21171671.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21171673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10585835 + 10585836.

It is an arithmetic number, because the mean of its divisors is an integer number (10585836).

Almost surely, 2^21171671 is an apocalyptic number.

21171671 is a deficient number, since it is larger than the sum of its proper divisors (1).

21171671 is an equidigital number, since it uses as much as digits as its factorization.

21171671 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 588, while the sum is 26.

The square root of 21171671 is about 4601.2684120794. The cubic root of 21171671 is about 276.6421676344.

Adding to 21171671 its reverse (17617112), we get a palindrome (38788783).

The spelling of 21171671 in words is "twenty-one million, one hundred seventy-one thousand, six hundred seventy-one".