16667561 has 4 divisors (see below), whose sum is σ = 16684500. Its totient is φ = 16650624.

The previous prime is 16667551. The next prime is 16667569. The reversal of 16667561 is 16576661.

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 9803161 + 6864400 = 3131^2 + 2620^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16667561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16667569) 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, 6896 + ... + 8993.

It is an arithmetic number, because the mean of its divisors is an integer number (4171125).

Almost surely, 2^16667561 is an apocalyptic number.

It is an amenable number.

16667561 is a deficient number, since it is larger than the sum of its proper divisors (16939).

16667561 is a wasteful number, since it uses less digits than its factorization.

16667561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16938.

The product of its digits is 45360, while the sum is 38.

The square root of 16667561 is about 4082.5924361856. The cubic root of 16667561 is about 255.4410462899.

The spelling of 16667561 in words is "sixteen million, six hundred sixty-seven thousand, five hundred sixty-one".