21034243 has 4 divisors (see below), whose sum is σ = 21072168. Its totient is φ = 20996320.

The previous prime is 21034231. The next prime is 21034249. The reversal of 21034243 is 34243012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21034243 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21034243.

It is not an unprimeable number, because it can be changed into a prime (21034249) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18118 + ... + 19243.

It is an arithmetic number, because the mean of its divisors is an integer number (5268042).

Almost surely, 2^21034243 is an apocalyptic number.

21034243 is a deficient number, since it is larger than the sum of its proper divisors (37925).

21034243 is an equidigital number, since it uses as much as digits as its factorization.

21034243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37924.

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 21034243 is about 4586.3103907171. The cubic root of 21034243 is about 276.0422946806.

Adding to 21034243 its reverse (34243012), we get a palindrome (55277255).

It can be divided in two parts, 210 and 34243, that added together give a triangular number (34453 = T₂₆₂).

The spelling of 21034243 in words is "twenty-one million, thirty-four thousand, two hundred forty-three".