161273681 has 6 divisors (see below), whose sum is σ = 163347282. Its totient is φ = 159226080.

The previous prime is 161273657. The next prime is 161273683. The reversal of 161273681 is 186372161.

It can be written as a sum of positive squares in only one way, i.e., 122323600 + 38950081 = 11060^2 + 6241^2 .

It is a de Polignac number, because none of the positive numbers 2^k-161273681 is a prime.

It is a super-3 number, since 3×161273681³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161273683) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6680 + ... + 19161.

It is an arithmetic number, because the mean of its divisors is an integer number (27224547).

Almost surely, 2^161273681 is an apocalyptic number.

It is an amenable number.

161273681 is a deficient number, since it is larger than the sum of its proper divisors (2073601).

161273681 is an frugal number, since it uses more digits than its factorization.

161273681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25999 (or 25920 counting only the distinct ones).

The product of its digits is 12096, while the sum is 35.

The square root of 161273681 is about 12699.3575034330. The cubic root of 161273681 is about 544.3202602122.

The spelling of 161273681 in words is "one hundred sixty-one million, two hundred seventy-three thousand, six hundred eighty-one".