16561320 has 64 divisors (see below), whose sum is σ = 51408000. Its totient is φ = 4263168.

The previous prime is 16561313. The next prime is 16561327. The reversal of 16561320 is 2316561.

It is an interprime number because it is at equal distance from previous prime (16561313) and next prime (16561327).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (16561327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1101 + ... + 5859.

It is an arithmetic number, because the mean of its divisors is an integer number (803250).

Almost surely, 2^16561320 is an apocalyptic number.

16561320 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 16561320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25704000).

16561320 is an abundant number, since it is smaller than the sum of its proper divisors (34846680).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16561320 is a wasteful number, since it uses less digits than its factorization.

16561320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4802 (or 4798 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 16561320 is about 4069.5601727951. The cubic root of 16561320 is about 254.8971519114.

Adding to 16561320 its reverse (2316561), we get a palindrome (18877881).

The spelling of 16561320 in words is "sixteen million, five hundred sixty-one thousand, three hundred twenty".