16561138 has 16 divisors (see below), whose sum is σ = 27256320. Its totient is φ = 7484400.

The previous prime is 16561093. The next prime is 16561147. The reversal of 16561138 is 83116561.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1903 + ... + 6061.

It is an arithmetic number, because the mean of its divisors is an integer number (1703520).

Almost surely, 2^16561138 is an apocalyptic number.

16561138 is a deficient number, since it is larger than the sum of its proper divisors (10695182).

16561138 is a wasteful number, since it uses less digits than its factorization.

16561138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4353.

The product of its digits is 4320, while the sum is 31.

The square root of 16561138 is about 4069.5378115948. The cubic root of 16561138 is about 254.8962181805.

Adding to 16561138 its reverse (83116561), we get a palindrome (99677699).

It can be divided in two parts, 165611 and 38, that added together give a square (165649 = 407²).

The spelling of 16561138 in words is "sixteen million, five hundred sixty-one thousand, one hundred thirty-eight".