21212043 has 4 divisors (see below), whose sum is σ = 28282728. Its totient is φ = 14141360.

The previous prime is 21212033. The next prime is 21212071. The reversal of 21212043 is 34021212.

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

It is a cyclic number.

It is not a de Polignac number, because 21212043 - 2⁶ = 21211979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21212033) 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 in 3 ways as a sum of consecutive naturals, for example, 3535338 + ... + 3535343.

It is an arithmetic number, because the mean of its divisors is an integer number (7070682).

Almost surely, 2^21212043 is an apocalyptic number.

21212043 is a deficient number, since it is larger than the sum of its proper divisors (7070685).

21212043 is an equidigital number, since it uses as much as digits as its factorization.

21212043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7070684.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21212043 is about 4605.6533738439. The cubic root of 21212043 is about 276.8178978356.

Adding to 21212043 its reverse (34021212), we get a palindrome (55233255).

The spelling of 21212043 in words is "twenty-one million, two hundred twelve thousand, forty-three".