21305043 has 24 divisors (see below), whose sum is σ = 31608096. Its totient is φ = 13824000.

The previous prime is 21305027. The next prime is 21305047. The reversal of 21305043 is 34050312.

It is not a de Polignac number, because 21305043 - 2⁴ = 21305027 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21305047) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 82771 + ... + 83027.

It is an arithmetic number, because the mean of its divisors is an integer number (1317004).

Almost surely, 2^21305043 is an apocalyptic number.

21305043 is a deficient number, since it is larger than the sum of its proper divisors (10303053).

21305043 is a wasteful number, since it uses less digits than its factorization.

21305043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 475 (or 472 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21305043 is about 4615.7386191161. The cubic root of 21305043 is about 277.2218591234.

Adding to 21305043 its reverse (34050312), we get a palindrome (55355355).

The spelling of 21305043 in words is "twenty-one million, three hundred five thousand, forty-three".