21212303205 has 32 divisors (see below), whose sum is σ = 34209912960. Its totient is φ = 11223509760.

The previous prime is 21212303201. The next prime is 21212303221. The reversal of 21212303205 is 50230321212.

It is not a de Polignac number, because 21212303205 - 2² = 21212303201 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212303201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 961195 + ... + 983015.

It is an arithmetic number, because the mean of its divisors is an integer number (1069059780).

Almost surely, 2^21212303205 is an apocalyptic number.

It is an amenable number.

21212303205 is a deficient number, since it is larger than the sum of its proper divisors (12997609755).

21212303205 is a wasteful number, since it uses less digits than its factorization.

21212303205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22341.

The product of its (nonzero) digits is 720, while the sum is 21.

Adding to 21212303205 its reverse (50230321212), we get a palindrome (71442624417).

The spelling of 21212303205 in words is "twenty-one billion, two hundred twelve million, three hundred three thousand, two hundred five".