16561511201 has 4 divisors (see below), whose sum is σ = 16561920000. Its totient is φ = 16561102404.

The previous prime is 16561511147. The next prime is 16561511303. The reversal of 16561511201 is 10211516561.

16561511201 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 10211516561 = 69697 ⋅146513.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16561511201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16561511501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 136001 + ... + 227198.

It is an arithmetic number, because the mean of its divisors is an integer number (4140480000).

Almost surely, 2^16561511201 is an apocalyptic number.

It is an amenable number.

16561511201 is a deficient number, since it is larger than the sum of its proper divisors (408799).

16561511201 is an equidigital number, since it uses as much as digits as its factorization.

16561511201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 408798.

The product of its (nonzero) digits is 1800, while the sum is 29.

The spelling of 16561511201 in words is "sixteen billion, five hundred sixty-one million, five hundred eleven thousand, two hundred one".