21243843 has 16 divisors (see below), whose sum is σ = 33129600. Its totient is φ = 13416840.

The previous prime is 21243841. The next prime is 21243857. The reversal of 21243843 is 34834212.

It is not a de Polignac number, because 21243843 - 2¹ = 21243841 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21243841) 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 in 15 ways as a sum of consecutive naturals, for example, 20193 + ... + 21218.

It is an arithmetic number, because the mean of its divisors is an integer number (2070600).

Almost surely, 2^21243843 is an apocalyptic number.

21243843 is a deficient number, since it is larger than the sum of its proper divisors (11885757).

21243843 is a wasteful number, since it uses less digits than its factorization.

21243843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41439 (or 41433 counting only the distinct ones).

The product of its digits is 4608, while the sum is 27.

The square root of 21243843 is about 4609.1043598513. The cubic root of 21243843 is about 276.9561591353.

The spelling of 21243843 in words is "twenty-one million, two hundred forty-three thousand, eight hundred forty-three".