16561131 has 4 divisors (see below), whose sum is σ = 22081512. Its totient is φ = 11040752.

The previous prime is 16561093. The next prime is 16561147. The reversal of 16561131 is 13116561.

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 16561131 - 2⁶ = 16561067 is a prime.

It is a super-2 number, since 2×16561131² = 548542119998322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (16566131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2760186 + ... + 2760191.

It is an arithmetic number, because the mean of its divisors is an integer number (5520378).

Almost surely, 2^16561131 is an apocalyptic number.

16561131 is a deficient number, since it is larger than the sum of its proper divisors (5520381).

16561131 is an equidigital number, since it uses as much as digits as its factorization.

16561131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5520380.

The product of its digits is 540, while the sum is 24.

The square root of 16561131 is about 4069.5369515462. The cubic root of 16561131 is about 254.8961822676.

Adding to 16561131 its reverse (13116561), we get a palindrome (29677692).

The spelling of 16561131 in words is "sixteen million, five hundred sixty-one thousand, one hundred thirty-one".