16681657 has 4 divisors (see below), whose sum is σ = 16707556. Its totient is φ = 16655760.

The previous prime is 16681649. The next prime is 16681661. The reversal of 16681657 is 75618661.

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

It can be written as a sum of positive squares in 2 ways, for example, as 13075456 + 3606201 = 3616^2 + 1899^2 .

It is a cyclic number.

It is not a de Polignac number, because 16681657 - 2³ = 16681649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16681667) 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, 11958 + ... + 13279.

It is an arithmetic number, because the mean of its divisors is an integer number (4176889).

Almost surely, 2^16681657 is an apocalyptic number.

It is an amenable number.

16681657 is a deficient number, since it is larger than the sum of its proper divisors (25899).

16681657 is an equidigital number, since it uses as much as digits as its factorization.

16681657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25898.

The product of its digits is 60480, while the sum is 40.

The square root of 16681657 is about 4084.3184253924. The cubic root of 16681657 is about 255.5130360752.

The spelling of 16681657 in words is "sixteen million, six hundred eighty-one thousand, six hundred fifty-seven".