21386291 has 2 divisors, whose sum is σ = 21386292. Its totient is φ = 21386290.

The previous prime is 21386279. The next prime is 21386293. The reversal of 21386291 is 19268312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21386291 is a prime.

Together with 21386293, 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 (21386293) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10693145 + 10693146.

It is an arithmetic number, because the mean of its divisors is an integer number (10693146).

Almost surely, 2^21386291 is an apocalyptic number.

21386291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21386291 is an equidigital number, since it uses as much as digits as its factorization.

21386291 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 32.

The square root of 21386291 is about 4624.5314357241. The cubic root of 21386291 is about 277.5738125753.

The spelling of 21386291 in words is "twenty-one million, three hundred eighty-six thousand, two hundred ninety-one".