999785758721 has 2 divisors, whose sum is σ = 999785758722. Its totient is φ = 999785758720.

The previous prime is 999785758679. The next prime is 999785758781. The reversal of 999785758721 is 127857587999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 538221780496 + 461563978225 = 733636^2 + 679385^2 .

It is a cyclic number.

It is not a de Polignac number, because 999785758721 - 2¹⁰ = 999785757697 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (999785758781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499892879360 + 499892879361.

It is an arithmetic number, because the mean of its divisors is an integer number (499892879361).

It is a Proth number, since it is equal to 476735 ⋅ 2²¹ + 1 and 476735 < 2²¹.

Almost surely, 2^999785758721 is an apocalyptic number.

It is an amenable number.

999785758721 is a deficient number, since it is larger than the sum of its proper divisors (1).

999785758721 is an equidigital number, since it uses as much as digits as its factorization.

999785758721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 800150400, while the sum is 77.

The spelling of 999785758721 in words is "nine hundred ninety-nine billion, seven hundred eighty-five million, seven hundred fifty-eight thousand, seven hundred twenty-one".