161748781 has 2 divisors, whose sum is σ = 161748782. Its totient is φ = 161748780.

The previous prime is 161748751. The next prime is 161748791. The reversal of 161748781 is 187847161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 156500100 + 5248681 = 12510^2 + 2291^2 .

It is a cyclic number.

It is not a de Polignac number, because 161748781 - 2¹⁹ = 161224493 is a prime.

It is a super-2 number, since 2×161748781² = 52325336309971922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161748751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80874390 + 80874391.

It is an arithmetic number, because the mean of its divisors is an integer number (80874391).

Almost surely, 2^161748781 is an apocalyptic number.

It is an amenable number.

161748781 is a deficient number, since it is larger than the sum of its proper divisors (1).

161748781 is an equidigital number, since it uses as much as digits as its factorization.

161748781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 75264, while the sum is 43.

The square root of 161748781 is about 12718.0494180515. The cubic root of 161748781 is about 544.8542448933.

The spelling of 161748781 in words is "one hundred sixty-one million, seven hundred forty-eight thousand, seven hundred eighty-one".