16647661 has 4 divisors (see below), whose sum is σ = 16656192. Its totient is φ = 16639132.

The previous prime is 16647647. The next prime is 16647703. The reversal of 16647661 is 16674661.

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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 16674661 = 353 ⋅47237.

It is a cyclic number.

It is not a de Polignac number, because 16647661 - 2¹⁵ = 16614893 is a prime.

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 16647661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16627661) 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, 270 + ... + 5776.

It is an arithmetic number, because the mean of its divisors is an integer number (4164048).

Almost surely, 2^16647661 is an apocalyptic number.

It is an amenable number.

16647661 is a deficient number, since it is larger than the sum of its proper divisors (8531).

16647661 is an equidigital number, since it uses as much as digits as its factorization.

16647661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8530.

The product of its digits is 36288, while the sum is 37.

The square root of 16647661 is about 4080.1545313873. The cubic root of 16647661 is about 255.3393457232.

Subtracting 16647661 from its reverse (16674661), we obtain a cube (27000 = 30³).

The spelling of 16647661 in words is "sixteen million, six hundred forty-seven thousand, six hundred sixty-one".