21042193 has 2 divisors, whose sum is σ = 21042194. Its totient is φ = 21042192.

The previous prime is 21042187. The next prime is 21042223. The reversal of 21042193 is 39124012.

21042193 is nontrivially palindromic in base 8.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20720704 + 321489 = 4552^2 + 567^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21042193 is a prime.

It is not a weakly prime, because it can be changed into another prime (21042103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521096 + 10521097.

It is an arithmetic number, because the mean of its divisors is an integer number (10521097).

Almost surely, 2^21042193 is an apocalyptic number.

It is an amenable number.

21042193 is a deficient number, since it is larger than the sum of its proper divisors (1).

21042193 is an equidigital number, since it uses as much as digits as its factorization.

21042193 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21042193 is about 4587.1770186031. The cubic root of 21042193 is about 276.0770675003.

The spelling of 21042193 in words is "twenty-one million, forty-two thousand, one hundred ninety-three".