16006561 has 4 divisors (see below), whose sum is σ = 16186500. Its totient is φ = 15826624.

The previous prime is 16006559. The next prime is 16006591. The reversal of 16006561 is 16560061.

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 2822400 + 13184161 = 1680^2 + 3631^2 .

It is a cyclic number.

It is not a de Polignac number, because 16006561 - 2¹ = 16006559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16006591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 89836 + ... + 90013.

It is an arithmetic number, because the mean of its divisors is an integer number (4046625).

Almost surely, 2^16006561 is an apocalyptic number.

It is an amenable number.

16006561 is a deficient number, since it is larger than the sum of its proper divisors (179939).

16006561 is an equidigital number, since it uses as much as digits as its factorization.

16006561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179938.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 16006561 is about 4000.8200409416. The cubic root of 16006561 is about 252.0186483638.

It can be divided in two parts, 1600 and 6561, that multiplied together give a square (10497600 = 3240²).

The spelling of 16006561 in words is "sixteen million, six thousand, five hundred sixty-one".