16664581 has 4 divisors (see below), whose sum is σ = 17389152. Its totient is φ = 15940012.

The previous prime is 16664579. The next prime is 16664587. The reversal of 16664581 is 18546661.

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.

It is not a de Polignac number, because 16664581 - 2¹ = 16664579 is a prime.

It is a super-2 number, since 2×16664581² = 555416519811122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16664581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16664587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 362251 + ... + 362296.

It is an arithmetic number, because the mean of its divisors is an integer number (4347288).

Almost surely, 2^16664581 is an apocalyptic number.

It is an amenable number.

16664581 is a deficient number, since it is larger than the sum of its proper divisors (724571).

16664581 is an equidigital number, since it uses as much as digits as its factorization.

16664581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 724570.

The product of its digits is 34560, while the sum is 37.

The square root of 16664581 is about 4082.2274556913. The cubic root of 16664581 is about 255.4258219131.

The spelling of 16664581 in words is "sixteen million, six hundred sixty-four thousand, five hundred eighty-one".