16661687 has 4 divisors (see below), whose sum is σ = 19041936. Its totient is φ = 14281440.

The previous prime is 16661681. The next prime is 16661707. The reversal of 16661687 is 78616661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 16661687 - 2⁸ = 16661431 is a prime.

It is a super-2 number, since 2×16661687² = 555223627371938, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16661681) 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, 1190114 + ... + 1190127.

It is an arithmetic number, because the mean of its divisors is an integer number (4760484).

Almost surely, 2^16661687 is an apocalyptic number.

16661687 is a deficient number, since it is larger than the sum of its proper divisors (2380249).

16661687 is an equidigital number, since it uses as much as digits as its factorization.

16661687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2380248.

The product of its digits is 72576, while the sum is 41.

The square root of 16661687 is about 4081.8729769556. The cubic root of 16661687 is about 255.4110351602.

The spelling of 16661687 in words is "sixteen million, six hundred sixty-one thousand, six hundred eighty-seven".