16561330 has 16 divisors (see below), whose sum is σ = 29968344. Its totient is φ = 6589440.

The previous prime is 16561327. The next prime is 16561339. The reversal of 16561330 is 3316561.

It can be written as a sum of positive squares in 4 ways, for example, as 5076009 + 11485321 = 2253^2 + 3389^2 .

It is a junction number, because it is equal to n+sod(n) for n = 16561295 and 16561304.

It is not an unprimeable number, because it can be changed into a prime (16561339) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2361 + ... + 6220.

Almost surely, 2^16561330 is an apocalyptic number.

16561330 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

16561330 is a deficient number, since it is larger than the sum of its proper divisors (13407014).

16561330 is a wasteful number, since it uses less digits than its factorization.

16561330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8781.

The product of its (nonzero) digits is 1620, while the sum is 25.

The square root of 16561330 is about 4069.5614014289. The cubic root of 16561330 is about 254.8972032151.

Adding to 16561330 its reverse (3316561), we get a palindrome (19877891).

The spelling of 16561330 in words is "sixteen million, five hundred sixty-one thousand, three hundred thirty".