21436871 has 2 divisors, whose sum is σ = 21436872. Its totient is φ = 21436870.

The previous prime is 21436853. The next prime is 21436873. The reversal of 21436871 is 17863412.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21436871 is a prime.

Together with 21436873, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21436873) 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, 10718435 + 10718436.

It is an arithmetic number, because the mean of its divisors is an integer number (10718436).

Almost surely, 2^21436871 is an apocalyptic number.

21436871 is a deficient number, since it is larger than the sum of its proper divisors (1).

21436871 is an equidigital number, since it uses as much as digits as its factorization.

21436871 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 32.

The square root of 21436871 is about 4629.9968682495. The cubic root of 21436871 is about 277.7924671284.

The spelling of 21436871 in words is "twenty-one million, four hundred thirty-six thousand, eight hundred seventy-one".