16561831947 has 4 divisors (see below), whose sum is σ = 22082442600. Its totient is φ = 11041221296.

The previous prime is 16561831943. The next prime is 16561832047. The reversal of 16561831947 is 74913816561.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 16561831947 - 2² = 16561831943 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16561831947.

It is not an unprimeable number, because it can be changed into a prime (16561831943) 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, 2760305322 + ... + 2760305327.

It is an arithmetic number, because the mean of its divisors is an integer number (5520610650).

Almost surely, 2^16561831947 is an apocalyptic number.

16561831947 is a deficient number, since it is larger than the sum of its proper divisors (5520610653).

16561831947 is an equidigital number, since it uses as much as digits as its factorization.

16561831947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5520610652.

The product of its digits is 1088640, while the sum is 51.

The spelling of 16561831947 in words is "sixteen billion, five hundred sixty-one million, eight hundred thirty-one thousand, nine hundred forty-seven".