21203291 has 2 divisors, whose sum is σ = 21203292. Its totient is φ = 21203290.

The previous prime is 21203279. The next prime is 21203293. The reversal of 21203291 is 19230212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21203291 is a prime.

Together with 21203293, 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 (21203293) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601645 + 10601646.

It is an arithmetic number, because the mean of its divisors is an integer number (10601646).

Almost surely, 2^21203291 is an apocalyptic number.

21203291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21203291 is an equidigital number, since it uses as much as digits as its factorization.

21203291 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 21203291 is about 4604.7031391828. The cubic root of 21203291 is about 276.7798212971.

The spelling of 21203291 in words is "twenty-one million, two hundred three thousand, two hundred ninety-one".