16531661543 has 4 divisors (see below), whose sum is σ = 17504112240. Its totient is φ = 15559210848.

The previous prime is 16531661507. The next prime is 16531661603. The reversal of 16531661543 is 34516613561.

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 16531661543 - 2⁸ = 16531661287 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 16531661543.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16531661243) 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, 486225323 + ... + 486225356.

It is an arithmetic number, because the mean of its divisors is an integer number (4376028060).

Almost surely, 2^16531661543 is an apocalyptic number.

16531661543 is a deficient number, since it is larger than the sum of its proper divisors (972450697).

16531661543 is an equidigital number, since it uses as much as digits as its factorization.

16531661543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 972450696.

The product of its digits is 194400, while the sum is 41.

The spelling of 16531661543 in words is "sixteen billion, five hundred thirty-one million, six hundred sixty-one thousand, five hundred forty-three".