21212342 has 4 divisors (see below), whose sum is σ = 31818516. Its totient is φ = 10606170.

The previous prime is 21212297. The next prime is 21212353. The reversal of 21212342 is 24321212.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21212342.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5303084 + ... + 5303087.

It is an arithmetic number, because the mean of its divisors is an integer number (7954629).

Almost surely, 2^21212342 is an apocalyptic number.

21212342 is a deficient number, since it is larger than the sum of its proper divisors (10606174).

21212342 is a wasteful number, since it uses less digits than its factorization.

21212342 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10606173.

The product of its digits is 192, while the sum is 17.

The square root of 21212342 is about 4605.6858338363. The cubic root of 21212342 is about 276.8191984829.

Adding to 21212342 its reverse (24321212), we get a palindrome (45533554).

The spelling of 21212342 in words is "twenty-one million, two hundred twelve thousand, three hundred forty-two".