16561772639 has 4 divisors (see below), whose sum is σ = 16604348280. Its totient is φ = 16519197000.

The previous prime is 16561772573. The next prime is 16561772641. The reversal of 16561772639 is 93627716561.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16561772639 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16566772639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21287237 + ... + 21288014.

It is an arithmetic number, because the mean of its divisors is an integer number (4151087070).

Almost surely, 2^16561772639 is an apocalyptic number.

16561772639 is a deficient number, since it is larger than the sum of its proper divisors (42575641).

16561772639 is an equidigital number, since it uses as much as digits as its factorization.

16561772639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42575640.

The product of its digits is 2857680, while the sum is 53.

The spelling of 16561772639 in words is "sixteen billion, five hundred sixty-one million, seven hundred seventy-two thousand, six hundred thirty-nine".