16561500 has 96 divisors (see below), whose sum is σ = 49288512. Its totient is φ = 4320000.

The previous prime is 16561469. The next prime is 16561507. The reversal of 16561500 is 516561.

16561500 = T₄₅₁ + T₄₅₂ + ... + T₅₇₅.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16561507) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 91410 + ... + 91590.

It is an arithmetic number, because the mean of its divisors is an integer number (513422).

Almost surely, 2^16561500 is an apocalyptic number.

16561500 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 16561500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24644256).

16561500 is an abundant number, since it is smaller than the sum of its proper divisors (32727012).

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

16561500 is a wasteful number, since it uses less digits than its factorization.

16561500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 264 (or 252 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 24.

The square root of 16561500 is about 4069.5822881470. The cubic root of 16561500 is about 254.8980753749.

The spelling of 16561500 in words is "sixteen million, five hundred sixty-one thousand, five hundred".