16561872 has 30 divisors (see below), whose sum is σ = 46350642. Its totient is φ = 5520576.

The previous prime is 16561861. The next prime is 16561889. The reversal of 16561872 is 27816561.

16561872 is a `hidden beast` number, since 16 + 561 + 87 + 2 = 666.

It can be written as a sum of positive squares in only one way, i.e., 16353936 + 207936 = 4044^2 + 456^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

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, 57363 + ... + 57650.

Almost surely, 2^16561872 is an apocalyptic number.

16561872 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

16561872 is an abundant number, since it is smaller than the sum of its proper divisors (29788770).

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

16561872 is a wasteful number, since it uses less digits than its factorization.

16561872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115027 (or 115018 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 16561872 is about 4069.6279928269. The cubic root of 16561872 is about 254.8999838448.

The spelling of 16561872 in words is "sixteen million, five hundred sixty-one thousand, eight hundred seventy-two".