16561801 has 4 divisors (see below), whose sum is σ = 16648704. Its totient is φ = 16474900.

The previous prime is 16561799. The next prime is 16561819. The reversal of 16561801 is 10816561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 16561801 - 2¹ = 16561799 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16561801.

It is not an unprimeable number, because it can be changed into a prime (16561861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43165 + ... + 43546.

It is an arithmetic number, because the mean of its divisors is an integer number (4162176).

Almost surely, 2^16561801 is an apocalyptic number.

It is an amenable number.

16561801 is a deficient number, since it is larger than the sum of its proper divisors (86903).

16561801 is an equidigital number, since it uses as much as digits as its factorization.

16561801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86902.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 16561801 is about 4069.6192696615. The cubic root of 16561801 is about 254.8996195960.

The spelling of 16561801 in words is "sixteen million, five hundred sixty-one thousand, eight hundred one".