21212343 has 6 divisors (see below), whose sum is σ = 30640064. Its totient is φ = 14141556.

The previous prime is 21212297. The next prime is 21212353. The reversal of 21212343 is 34321212.

21212343 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It is not a de Polignac number, because 21212343 - 2⁹ = 21211831 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212353) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1178455 + ... + 1178472.

Almost surely, 2^21212343 is an apocalyptic number.

21212343 is a deficient number, since it is larger than the sum of its proper divisors (9427721).

21212343 is a wasteful number, since it uses less digits than its factorization.

21212343 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2356933 (or 2356930 counting only the distinct ones).

The product of its digits is 288, while the sum is 18.

The square root of 21212343 is about 4605.6859423977. The cubic root of 21212343 is about 276.8192028329.

Adding to 21212343 its reverse (34321212), we get a palindrome (55533555).

The spelling of 21212343 in words is "twenty-one million, two hundred twelve thousand, three hundred forty-three".