16631365561 has 4 divisors (see below), whose sum is σ = 16786798992. Its totient is φ = 16475932132.

The previous prime is 16631365511. The next prime is 16631365567. The reversal of 16631365561 is 16556313661.

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 16631365561 - 2¹⁵ = 16631332793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16631365567) 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, 77716555 + ... + 77716768.

It is an arithmetic number, because the mean of its divisors is an integer number (4196699748).

Almost surely, 2^16631365561 is an apocalyptic number.

It is an amenable number.

16631365561 is a deficient number, since it is larger than the sum of its proper divisors (155433431).

16631365561 is a wasteful number, since it uses less digits than its factorization.

16631365561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155433430.

The product of its digits is 291600, while the sum is 43.

The spelling of 16631365561 in words is "sixteen billion, six hundred thirty-one million, three hundred sixty-five thousand, five hundred sixty-one".