21123213112 has 16 divisors (see below), whose sum is σ = 39612895200. Its totient is φ = 10559774400.

The previous prime is 21123213109. The next prime is 21123213143. The reversal of 21123213112 is 21131232112.

It is a self number, because there is not a number n which added to its sum of digits gives 21123213112.

It is a congruent 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 3 ways as a sum of consecutive naturals, for example, 179389 + ... + 272812.

It is an arithmetic number, because the mean of its divisors is an integer number (2475805950).

Almost surely, 2^21123213112 is an apocalyptic number.

It is an amenable number.

21123213112 is a deficient number, since it is larger than the sum of its proper divisors (18489682088).

21123213112 is a wasteful number, since it uses less digits than its factorization.

21123213112 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 458046 (or 458042 counting only the distinct ones).

The product of its digits is 144, while the sum is 19.

Adding to 21123213112 its reverse (21131232112), we get a palindrome (42254445224).

The spelling of 21123213112 in words is "twenty-one billion, one hundred twenty-three million, two hundred thirteen thousand, one hundred twelve".