16166561 has 4 divisors (see below), whose sum is σ = 16248000. Its totient is φ = 16085124.

The previous prime is 16166533. The next prime is 16166569. The reversal of 16166561 is 16566161.

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 an emirpimes, since its reverse is a distinct semiprime: 16566161 = 2843 ⋅5827.

It is a cyclic number.

It is not a de Polignac number, because 16166561 - 2¹⁰ = 16165537 is a prime.

It is a super-2 number, since 2×16166561² = 522715389133442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16166569) 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, 40421 + ... + 40818.

It is an arithmetic number, because the mean of its divisors is an integer number (4062000).

Almost surely, 2^16166561 is an apocalyptic number.

It is an amenable number.

16166561 is a deficient number, since it is larger than the sum of its proper divisors (81439).

16166561 is an equidigital number, since it uses as much as digits as its factorization.

16166561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81438.

The product of its digits is 6480, while the sum is 32.

The square root of 16166561 is about 4020.7662205107. The cubic root of 16166561 is about 252.8555837109.

The spelling of 16166561 in words is "sixteen million, one hundred sixty-six thousand, five hundred sixty-one".