1165817981 has 2 divisors, whose sum is σ = 1165817982. Its totient is φ = 1165817980.

The previous prime is 1165817971. The next prime is 1165817987. The reversal of 1165817981 is 1897185611.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 802305625 + 363512356 = 28325^2 + 19066^2 .

It is a cyclic number.

It is not a de Polignac number, because 1165817981 - 2¹⁰ = 1165816957 is a prime.

It is a super-2 number, since 2×1165817981² = 2718263129645832722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1165817987) 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, 582908990 + 582908991.

It is an arithmetic number, because the mean of its divisors is an integer number (582908991).

Almost surely, 2^1165817981 is an apocalyptic number.

It is an amenable number.

1165817981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1165817981 is an equidigital number, since it uses as much as digits as its factorization.

1165817981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120960, while the sum is 47.

The square root of 1165817981 is about 34144.0768069661. The cubic root of 1165817981 is about 1052.4712708366.

The spelling of 1165817981 in words is "one billion, one hundred sixty-five million, eight hundred seventeen thousand, nine hundred eighty-one".