991660853 has 2 divisors, whose sum is σ = 991660854. Its totient is φ = 991660852.

The previous prime is 991660811. The next prime is 991660877. The reversal of 991660853 is 358066199.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 927628849 + 64032004 = 30457^2 + 8002^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991660853 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 991660798 and 991660807.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991660253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495830426 + 495830427.

It is an arithmetic number, because the mean of its divisors is an integer number (495830427).

Almost surely, 2^991660853 is an apocalyptic number.

It is an amenable number.

991660853 is a deficient number, since it is larger than the sum of its proper divisors (1).

991660853 is an equidigital number, since it uses as much as digits as its factorization.

991660853 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 349920, while the sum is 47.

The square root of 991660853 is about 31490.6470717894. The cubic root of 991660853 is about 997.2125215166.

The spelling of 991660853 in words is "nine hundred ninety-one million, six hundred sixty thousand, eight hundred fifty-three".