16561100 has 18 divisors (see below), whose sum is σ = 35937804. Its totient is φ = 6624400.

The previous prime is 16561093. The next prime is 16561147. The reversal of 16561100 is 116561.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 82706 + ... + 82905.

Almost surely, 2^16561100 is an apocalyptic number.

16561100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16561100 is an abundant number, since it is smaller than the sum of its proper divisors (19376704).

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

16561100 is a wasteful number, since it uses less digits than its factorization.

16561100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165625 (or 165618 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 16561100 is about 4069.5331427573. The cubic root of 16561100 is about 254.8960232248.

Adding to 16561100 its reverse (116561), we get a palindrome (16677661).

It can be divided in two parts, 16561 and 100, that added together give a palindrome (16661).

The spelling of 16561100 in words is "sixteen million, five hundred sixty-one thousand, one hundred".