2491163981 has 2 divisors, whose sum is σ = 2491163982. Its totient is φ = 2491163980.

The previous prime is 2491163963. The next prime is 2491164001. The reversal of 2491163981 is 1893611942.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2485919881 + 5244100 = 49859^2 + 2290^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2491163981 is a prime.

It is a super-2 number, since 2×2491163981² = 12411795960463536722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2491163951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1245581990 + 1245581991.

It is an arithmetic number, because the mean of its divisors is an integer number (1245581991).

Almost surely, 2^2491163981 is an apocalyptic number.

It is an amenable number.

2491163981 is a deficient number, since it is larger than the sum of its proper divisors (1).

2491163981 is an equidigital number, since it uses as much as digits as its factorization.

2491163981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 93312, while the sum is 44.

The square root of 2491163981 is about 49911.5615964878. The cubic root of 2491163981 is about 1355.6079444027.

The spelling of 2491163981 in words is "two billion, four hundred ninety-one million, one hundred sixty-three thousand, nine hundred eighty-one".