21043340429 has 2 divisors, whose sum is σ = 21043340430. Its totient is φ = 21043340428.

The previous prime is 21043340413. The next prime is 21043340443. The reversal of 21043340429 is 92404334012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15327678025 + 5715662404 = 123805^2 + 75602^2 .

It is a cyclic number.

It is not a de Polignac number, because 21043340429 - 2⁴ = 21043340413 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21043340395 and 21043340404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21043348429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521670214 + 10521670215.

It is an arithmetic number, because the mean of its divisors is an integer number (10521670215).

Almost surely, 2^21043340429 is an apocalyptic number.

It is an amenable number.

21043340429 is a deficient number, since it is larger than the sum of its proper divisors (1).

21043340429 is an equidigital number, since it uses as much as digits as its factorization.

21043340429 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 32.

The spelling of 21043340429 in words is "twenty-one billion, forty-three million, three hundred forty thousand, four hundred twenty-nine".