21793231 has 2 divisors, whose sum is σ = 21793232. Its totient is φ = 21793230.

The previous prime is 21793223. The next prime is 21793241. The reversal of 21793231 is 13239712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21793231 - 2³ = 21793223 is a prime.

It is a super-2 number, since 2×21793231² = 949889834838722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21793231.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21793241) 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, 10896615 + 10896616.

It is an arithmetic number, because the mean of its divisors is an integer number (10896616).

Almost surely, 2^21793231 is an apocalyptic number.

21793231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21793231 is an equidigital number, since it uses as much as digits as its factorization.

21793231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2268, while the sum is 28.

The square root of 21793231 is about 4668.3220754357. The cubic root of 21793231 is about 279.3233277473.

The spelling of 21793231 in words is "twenty-one million, seven hundred ninety-three thousand, two hundred thirty-one".