21986243 has 2 divisors, whose sum is σ = 21986244. Its totient is φ = 21986242.

The previous prime is 21986233. The next prime is 21986269. The reversal of 21986243 is 34268912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21986243 - 2⁴ = 21986227 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21986203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10993121 + 10993122.

It is an arithmetic number, because the mean of its divisors is an integer number (10993122).

Almost surely, 2^21986243 is an apocalyptic number.

21986243 is a deficient number, since it is larger than the sum of its proper divisors (1).

21986243 is an equidigital number, since it uses as much as digits as its factorization.

21986243 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20736, while the sum is 35.

The square root of 21986243 is about 4688.9490293668. The cubic root of 21986243 is about 280.1455153493.

The spelling of 21986243 in words is "twenty-one million, nine hundred eighty-six thousand, two hundred forty-three".