16501661 has 4 divisors (see below), whose sum is σ = 18001824. Its totient is φ = 15001500.

The previous prime is 16501643. The next prime is 16501711. The reversal of 16501661 is 16610561.

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 a cyclic number.

It is not a de Polignac number, because 16501661 - 2²² = 12307357 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 16501661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16501361) 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, 750065 + ... + 750086.

It is an arithmetic number, because the mean of its divisors is an integer number (4500456).

Almost surely, 2^16501661 is an apocalyptic number.

16501661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16501661 is a deficient number, since it is larger than the sum of its proper divisors (1500163).

16501661 is a wasteful number, since it uses less digits than its factorization.

16501661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1500162.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 16501661 is about 4062.2236521393. The cubic root of 16501661 is about 254.5907108424.

Subtracting 16501661 from its reverse (16610561), we obtain a square (108900 = 330²).

The spelling of 16501661 in words is "sixteen million, five hundred one thousand, six hundred sixty-one".