161081531 has 4 divisors (see below), whose sum is σ = 173472432. Its totient is φ = 148690632.

The previous prime is 161081527. The next prime is 161081533. The reversal of 161081531 is 135180161.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 161081531 - 2² = 161081527 is a prime.

It is a super-2 number, since 2×161081531² = 51894519258607922, 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 161081531.

It is not an unprimeable number, because it can be changed into a prime (161081533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6195431 + ... + 6195456.

It is an arithmetic number, because the mean of its divisors is an integer number (43368108).

Almost surely, 2^161081531 is an apocalyptic number.

161081531 is a deficient number, since it is larger than the sum of its proper divisors (12390901).

161081531 is a wasteful number, since it uses less digits than its factorization.

161081531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12390900.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 161081531 is about 12691.7899052892. The cubic root of 161081531 is about 544.1039969770.

The spelling of 161081531 in words is "one hundred sixty-one million, eighty-one thousand, five hundred thirty-one".