21043423791 has 12 divisors (see below), whose sum is σ = 32734214968. Its totient is φ = 12949799184.

The previous prime is 21043423789. The next prime is 21043423823. The reversal of 21043423791 is 19732434012.

It is a happy number.

21043423791 is a `hidden beast` number, since 210 + 434 + 2 + 3 + 7 + 9 + 1 = 666.

It is not a de Polignac number, because 21043423791 - 2¹ = 21043423789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21043423691) 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 11 ways as a sum of consecutive naturals, for example, 89929045 + ... + 89929278.

Almost surely, 2^21043423791 is an apocalyptic number.

21043423791 is a deficient number, since it is larger than the sum of its proper divisors (11690791177).

21043423791 is a wasteful number, since it uses less digits than its factorization.

21043423791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179858342 (or 179858339 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The spelling of 21043423791 in words is "twenty-one billion, forty-three million, four hundred twenty-three thousand, seven hundred ninety-one".