21243203412 has 12 divisors (see below), whose sum is σ = 49567474656. Its totient is φ = 7081067800.

The previous prime is 21243203381. The next prime is 21243203419. The reversal of 21243203412 is 21430234212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243203419) 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 3 ways as a sum of consecutive naturals, for example, 885133464 + ... + 885133487.

It is an arithmetic number, because the mean of its divisors is an integer number (4130622888).

Almost surely, 2^21243203412 is an apocalyptic number.

It is an amenable number.

21243203412 is an abundant number, since it is smaller than the sum of its proper divisors (28324271244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21243203412 is a wasteful number, since it uses less digits than its factorization.

21243203412 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1770266958 (or 1770266956 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

Adding to 21243203412 its reverse (21430234212), we get a palindrome (42673437624).

The spelling of 21243203412 in words is "twenty-one billion, two hundred forty-three million, two hundred three thousand, four hundred twelve".