16561642 has 4 divisors (see below), whose sum is σ = 24842466. Its totient is φ = 8280820.

The previous prime is 16561627. The next prime is 16561661. The reversal of 16561642 is 24616561.

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

It can be written as a sum of positive squares in only one way, i.e., 10949481 + 5612161 = 3309^2 + 2369^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4140409 + ... + 4140412.

Almost surely, 2^16561642 is an apocalyptic number.

16561642 is a deficient number, since it is larger than the sum of its proper divisors (8280824).

16561642 is an equidigital number, since it uses as much as digits as its factorization.

16561642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8280823.

The product of its digits is 8640, while the sum is 31.

The square root of 16561642 is about 4069.5997346176. The cubic root of 16561642 is about 254.8988038802.

The spelling of 16561642 in words is "sixteen million, five hundred sixty-one thousand, six hundred forty-two".