16561657 has 12 divisors (see below), whose sum is σ = 19888896. Its totient is φ = 13736520.

The previous prime is 16561627. The next prime is 16561661. The reversal of 16561657 is 75616561.

It is not a de Polignac number, because 16561657 - 2¹⁹ = 16037369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16561627) 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 11 ways as a sum of consecutive naturals, for example, 3933 + ... + 6970.

It is an arithmetic number, because the mean of its divisors is an integer number (1657408).

Almost surely, 2^16561657 is an apocalyptic number.

It is an amenable number.

16561657 is a deficient number, since it is larger than the sum of its proper divisors (3327239).

16561657 is a wasteful number, since it uses less digits than its factorization.

16561657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10948 (or 10941 counting only the distinct ones).

The product of its digits is 37800, while the sum is 37.

The square root of 16561657 is about 4069.6015775503. The cubic root of 16561657 is about 254.8988808348.

The spelling of 16561657 in words is "sixteen million, five hundred sixty-one thousand, six hundred fifty-seven".