16500661 has 4 divisors (see below), whose sum is σ = 16509024. Its totient is φ = 16492300.

The previous prime is 16500647. The next prime is 16500677. The reversal of 16500661 is 16600561.

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: 16600561 = 173 ⋅95957.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16500661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16500641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 606 + ... + 5776.

It is an arithmetic number, because the mean of its divisors is an integer number (4127256).

Almost surely, 2^16500661 is an apocalyptic number.

It is an amenable number.

16500661 is a deficient number, since it is larger than the sum of its proper divisors (8363).

16500661 is an equidigital number, since it uses as much as digits as its factorization.

16500661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8362.

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

The square root of 16500661 is about 4062.1005649787. The cubic root of 16500661 is about 254.5855680096.

It can be divided in two parts, 16500 and 661, that added together give a square (17161 = 131²).

The spelling of 16500661 in words is "sixteen million, five hundred thousand, six hundred sixty-one".