1157161981 has 2 divisors, whose sum is σ = 1157161982. Its totient is φ = 1157161980.

The previous prime is 1157161969. The next prime is 1157162029. The reversal of 1157161981 is 1891617511.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1117899225 + 39262756 = 33435^2 + 6266^2 .

It is a cyclic number.

It is not a de Polignac number, because 1157161981 - 2²⁷ = 1022944253 is a prime.

It is a super-2 number, since 2×1157161981² = 2678047700543688722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1157161381) 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, 578580990 + 578580991.

It is an arithmetic number, because the mean of its divisors is an integer number (578580991).

Almost surely, 2^1157161981 is an apocalyptic number.

It is an amenable number.

1157161981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1157161981 is an equidigital number, since it uses as much as digits as its factorization.

1157161981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15120, while the sum is 40.

The square root of 1157161981 is about 34017.0836639474. The cubic root of 1157161981 is about 1049.8599907043.

The spelling of 1157161981 in words is "one billion, one hundred fifty-seven million, one hundred sixty-one thousand, nine hundred eighty-one".