21709490843 has 2 divisors, whose sum is σ = 21709490844. Its totient is φ = 21709490842.

The previous prime is 21709490833. The next prime is 21709490849. The reversal of 21709490843 is 34809490712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21709490843 - 2⁴ = 21709490827 is a prime.

It is not a weakly prime, because it can be changed into another prime (21709490849) 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, 10854745421 + 10854745422.

It is an arithmetic number, because the mean of its divisors is an integer number (10854745422).

Almost surely, 2^21709490843 is an apocalyptic number.

21709490843 is a deficient number, since it is larger than the sum of its proper divisors (1).

21709490843 is an equidigital number, since it uses as much as digits as its factorization.

21709490843 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 435456, while the sum is 47.

The spelling of 21709490843 in words is "twenty-one billion, seven hundred nine million, four hundred ninety thousand, eight hundred forty-three".