161159581 has 4 divisors (see below), whose sum is σ = 175810464. Its totient is φ = 146508700.

The previous prime is 161159549. The next prime is 161159587. The reversal of 161159581 is 185951161.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 161159581 - 2⁵ = 161159549 is a prime.

It is a super-2 number, since 2×161159581² = 51944821096191122, 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 161159581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161159587) 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, 7325425 + ... + 7325446.

It is an arithmetic number, because the mean of its divisors is an integer number (43952616).

Almost surely, 2^161159581 is an apocalyptic number.

161159581 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

161159581 is a deficient number, since it is larger than the sum of its proper divisors (14650883).

161159581 is a wasteful number, since it uses less digits than its factorization.

161159581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14650882.

The product of its digits is 10800, while the sum is 37.

The square root of 161159581 is about 12694.8643553210. The cubic root of 161159581 is about 544.1918623364.

The spelling of 161159581 in words is "one hundred sixty-one million, one hundred fifty-nine thousand, five hundred eighty-one".