21193231 has 2 divisors, whose sum is σ = 21193232. Its totient is φ = 21193230.

The previous prime is 21193223. The next prime is 21193247. The reversal of 21193231 is 13239112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21193231 - 2³ = 21193223 is a prime.

It is a super-2 number, since 2×21193231² = 898306080438722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21193201) 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, 10596615 + 10596616.

It is an arithmetic number, because the mean of its divisors is an integer number (10596616).

Almost surely, 2^21193231 is an apocalyptic number.

21193231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21193231 is an equidigital number, since it uses as much as digits as its factorization.

21193231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 324, while the sum is 22.

The square root of 21193231 is about 4603.6106481761. The cubic root of 21193231 is about 276.7360412147.

The spelling of 21193231 in words is "twenty-one million, one hundred ninety-three thousand, two hundred thirty-one".