21043029991 has 2 divisors, whose sum is σ = 21043029992. Its totient is φ = 21043029990.

The previous prime is 21043029979. The next prime is 21043030003. The reversal of 21043029991 is 19992034012.

It is a balanced prime because it is at equal distance from previous prime (21043029979) and next prime (21043030003).

It is a cyclic number.

It is not a de Polignac number, because 21043029991 - 2⁷ = 21043029863 is a prime.

It is a super-2 number, since 2×21043029991² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21043029191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521514995 + 10521514996.

It is an arithmetic number, because the mean of its divisors is an integer number (10521514996).

Almost surely, 2^21043029991 is an apocalyptic number.

21043029991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21043029991 is an equidigital number, since it uses as much as digits as its factorization.

21043029991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 34992, while the sum is 40.

The spelling of 21043029991 in words is "twenty-one billion, forty-three million, twenty-nine thousand, nine hundred ninety-one".