999916830721 has 2 divisors, whose sum is σ = 999916830722. Its totient is φ = 999916830720.

The previous prime is 999916830713. The next prime is 999916830769. The reversal of 999916830721 is 127038619999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 525278507121 + 474638323600 = 724761^2 + 688940^2 .

It is a cyclic number.

It is not a de Polignac number, because 999916830721 - 2³ = 999916830713 is a prime.

It is not a weakly prime, because it can be changed into another prime (999916830421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499958415360 + 499958415361.

It is an arithmetic number, because the mean of its divisors is an integer number (499958415361).

It is a Proth number, since it is equal to 953595 ⋅ 2²⁰ + 1 and 953595 < 2²⁰.

Almost surely, 2^999916830721 is an apocalyptic number.

It is an amenable number.

999916830721 is a deficient number, since it is larger than the sum of its proper divisors (1).

999916830721 is an equidigital number, since it uses as much as digits as its factorization.

999916830721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13226976, while the sum is 64.

It can be divided in two parts, 9999168 and 30721, that added together give a square (10029889 = 3167²).

The spelling of 999916830721 in words is "nine hundred ninety-nine billion, nine hundred sixteen million, eight hundred thirty thousand, seven hundred twenty-one".