161500681 has 8 divisors (see below), whose sum is σ = 171145800. Its totient is φ = 152127360.

The previous prime is 161500657. The next prime is 161500711. The reversal of 161500681 is 186005161.

It can be written as a sum of positive squares in 4 ways, for example, as 210681 + 161290000 = 459^2 + 12700^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161500681 - 2⁵ = 161500649 is a prime.

It is a super-2 number, since 2×161500681² = 52164939926927522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161500621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 66726 + ... + 69103.

It is an arithmetic number, because the mean of its divisors is an integer number (21393225).

Almost surely, 2^161500681 is an apocalyptic number.

It is an amenable number.

161500681 is a deficient number, since it is larger than the sum of its proper divisors (9645119).

161500681 is a wasteful number, since it uses less digits than its factorization.

161500681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135899.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 161500681 is about 12708.2918206972. The cubic root of 161500681 is about 544.5755256119.

The spelling of 161500681 in words is "one hundred sixty-one million, five hundred thousand, six hundred eighty-one".