161236681 has 2 divisors, whose sum is σ = 161236682. Its totient is φ = 161236680.

The previous prime is 161236657. The next prime is 161236697. The reversal of 161236681 is 186632161.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 132710400 + 28526281 = 11520^2 + 5341^2 .

It is an emirp because it is prime and its reverse (186632161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161236681 - 2⁹ = 161236169 is a prime.

It is a super-2 number, since 2×161236681² = 51994534599791522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161236631) 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, 80618340 + 80618341.

It is an arithmetic number, because the mean of its divisors is an integer number (80618341).

Almost surely, 2^161236681 is an apocalyptic number.

It is an amenable number.

161236681 is a deficient number, since it is larger than the sum of its proper divisors (1).

161236681 is an equidigital number, since it uses as much as digits as its factorization.

161236681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 34.

The square root of 161236681 is about 12697.9006532576. The cubic root of 161236681 is about 544.2786303776.

The spelling of 161236681 in words is "one hundred sixty-one million, two hundred thirty-six thousand, six hundred eighty-one".