161518681 has 9 divisors (see below), whose sum is σ = 164745973. Its totient is φ = 158354140.

The previous prime is 161518663. The next prime is 161518703. The reversal of 161518681 is 186815161.

The square root of 161518681 is 12709.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 161518681 - 2⁹ = 161518169 is a prime.

It is a super-2 number, since 2×161518681² = 52176568623959522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161518681.

It is not an unprimeable number, because it can be changed into a prime (161518631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 902250 + ... + 902428.

Almost surely, 2^161518681 is an apocalyptic number.

161518681 is the 12709-th square number.

161518681 is the 6355-th centered octagonal number.

It is an amenable number.

161518681 is a deficient number, since it is larger than the sum of its proper divisors (3227292).

161518681 is an frugal number, since it uses more digits than its factorization.

161518681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500 (or 250 counting only the distinct ones).

The product of its digits is 11520, while the sum is 37.

The cubic root of 161518681 is about 544.5957566831.

The spelling of 161518681 in words is "one hundred sixty-one million, five hundred eighteen thousand, six hundred eighty-one".