21213243305 has 16 divisors (see below), whose sum is σ = 25820201088. Its totient is φ = 16729440000.

The previous prime is 21213243283. The next prime is 21213243313. The reversal of 21213243305 is 50334231212.

It is a happy number.

It is not a de Polignac number, because 21213243305 - 2⁸ = 21213243049 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 8336 + ... + 206145.

It is an arithmetic number, because the mean of its divisors is an integer number (1613762568).

Almost surely, 2^21213243305 is an apocalyptic number.

It is an amenable number.

21213243305 is a deficient number, since it is larger than the sum of its proper divisors (4606957783).

21213243305 is a wasteful number, since it uses less digits than its factorization.

21213243305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214768.

The product of its (nonzero) digits is 4320, while the sum is 26.

Adding to 21213243305 its reverse (50334231212), we get a palindrome (71547474517).

The spelling of 21213243305 in words is "twenty-one billion, two hundred thirteen million, two hundred forty-three thousand, three hundred five".