161367581 has 4 divisors (see below), whose sum is σ = 161430972. Its totient is φ = 161304192.

The previous prime is 161367559. The next prime is 161367607. The reversal of 161367581 is 185763161.

161367581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 84015556 + 77352025 = 9166^2 + 8795^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161367581 is a prime.

It is a super-2 number, since 2×161367581² = 52078992395583122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161367541) 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, 27710 + ... + 33023.

It is an arithmetic number, because the mean of its divisors is an integer number (40357743).

Almost surely, 2^161367581 is an apocalyptic number.

It is an amenable number.

161367581 is a deficient number, since it is larger than the sum of its proper divisors (63391).

161367581 is an equidigital number, since it uses as much as digits as its factorization.

161367581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63390.

The product of its digits is 30240, while the sum is 38.

The square root of 161367581 is about 12703.0540028766. The cubic root of 161367581 is about 544.4258814054.

The spelling of 161367581 in words is "one hundred sixty-one million, three hundred sixty-seven thousand, five hundred eighty-one".