21391133 has 2 divisors, whose sum is σ = 21391134. Its totient is φ = 21391132.

The previous prime is 21391129. The next prime is 21391187. The reversal of 21391133 is 33119312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20052484 + 1338649 = 4478^2 + 1157^2 .

It is a cyclic number.

It is not a de Polignac number, because 21391133 - 2² = 21391129 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21391099 and 21391108.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21391193) 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, 10695566 + 10695567.

It is an arithmetic number, because the mean of its divisors is an integer number (10695567).

Almost surely, 2^21391133 is an apocalyptic number.

It is an amenable number.

21391133 is a deficient number, since it is larger than the sum of its proper divisors (1).

21391133 is an equidigital number, since it uses as much as digits as its factorization.

21391133 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 486, while the sum is 23.

The square root of 21391133 is about 4625.0549185929. The cubic root of 21391133 is about 277.5947591868.

The spelling of 21391133 in words is "twenty-one million, three hundred ninety-one thousand, one hundred thirty-three".