16161581 has 4 divisors (see below), whose sum is σ = 16169664. Its totient is φ = 16153500.

The previous prime is 16161569. The next prime is 16161589. The reversal of 16161581 is 18516161.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18516161 = 71 ⋅260791.

It is a cyclic number.

It is not a de Polignac number, because 16161581 - 2¹⁴ = 16145197 is a prime.

It is a super-2 number, since 2×16161581² = 522393400839122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16161589) 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, 1406 + ... + 5856.

It is an arithmetic number, because the mean of its divisors is an integer number (4042416).

Almost surely, 2^16161581 is an apocalyptic number.

It is an amenable number.

16161581 is a deficient number, since it is larger than the sum of its proper divisors (8083).

16161581 is an equidigital number, since it uses as much as digits as its factorization.

16161581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8082.

The product of its digits is 1440, while the sum is 29.

The square root of 16161581 is about 4020.1468878637. The cubic root of 16161581 is about 252.8296175592.

The spelling of 16161581 in words is "sixteen million, one hundred sixty-one thousand, five hundred eighty-one".