21366197 has 2 divisors, whose sum is σ = 21366198. Its totient is φ = 21366196.

The previous prime is 21366187. The next prime is 21366221. The reversal of 21366197 is 79166312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10699441 + 10666756 = 3271^2 + 3266^2 .

It is a cyclic number.

It is not a de Polignac number, because 21366197 - 2⁴ = 21366181 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21366187) 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, 10683098 + 10683099.

It is an arithmetic number, because the mean of its divisors is an integer number (10683099).

Almost surely, 2^21366197 is an apocalyptic number.

It is an amenable number.

21366197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21366197 is an equidigital number, since it uses as much as digits as its factorization.

21366197 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13608, while the sum is 35.

The square root of 21366197 is about 4622.3583807403. The cubic root of 21366197 is about 277.4868516347.

The spelling of 21366197 in words is "twenty-one million, three hundred sixty-six thousand, one hundred ninety-seven".