781181161 has 6 divisors (see below), whose sum is σ = 829836350. Its totient is φ = 735229056.

The previous prime is 781181147. The next prime is 781181171. The reversal of 781181161 is 161181187.

It can be written as a sum of positive squares in 3 ways, for example, as 583947225 + 197233936 = 24165^2 + 14044^2 .

It is a de Polignac number, because none of the positive numbers 2^k-781181161 is a prime.

It is a super-3 number, since 3×781181161³ (a number of 28 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781181101) 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 in 5 ways as a sum of consecutive naturals, for example, 1351236 + ... + 1351813.

Almost surely, 2^781181161 is an apocalyptic number.

It is an amenable number.

781181161 is a deficient number, since it is larger than the sum of its proper divisors (48655189).

781181161 is a wasteful number, since it uses less digits than its factorization.

781181161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2703083 (or 2703066 counting only the distinct ones).

The product of its digits is 2688, while the sum is 34.

The square root of 781181161 is about 27949.6182621516. The cubic root of 781181161 is about 920.9808226608.

The spelling of 781181161 in words is "seven hundred eighty-one million, one hundred eighty-one thousand, one hundred sixty-one".