21273191 has 2 divisors, whose sum is σ = 21273192. Its totient is φ = 21273190.

The previous prime is 21273181. The next prime is 21273253. The reversal of 21273191 is 19137212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21273191 - 2⁶ = 21273127 is a prime.

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 21273191.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21273101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10636595 + 10636596.

It is an arithmetic number, because the mean of its divisors is an integer number (10636596).

Almost surely, 2^21273191 is an apocalyptic number.

21273191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21273191 is an equidigital number, since it uses as much as digits as its factorization.

21273191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 756, while the sum is 26.

The square root of 21273191 is about 4612.2869598497. The cubic root of 21273191 is about 277.0836371577.

The spelling of 21273191 in words is "twenty-one million, two hundred seventy-three thousand, one hundred ninety-one".