21843397 has 2 divisors, whose sum is σ = 21843398. Its totient is φ = 21843396.

The previous prime is 21843383. The next prime is 21843403. The reversal of 21843397 is 79334812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19766916 + 2076481 = 4446^2 + 1441^2 .

It is a cyclic number.

It is not a de Polignac number, because 21843397 - 2¹¹ = 21841349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21843347) 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, 10921698 + 10921699.

It is an arithmetic number, because the mean of its divisors is an integer number (10921699).

Almost surely, 2^21843397 is an apocalyptic number.

It is an amenable number.

21843397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21843397 is an equidigital number, since it uses as much as digits as its factorization.

21843397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 37.

The square root of 21843397 is about 4673.6920095359. The cubic root of 21843397 is about 279.5374889844.

The spelling of 21843397 in words is "twenty-one million, eight hundred forty-three thousand, three hundred ninety-seven".