15661561542543 has 32 divisors (see below), whose sum is σ = 26519633861120. Its totient is φ = 8948551049280.

The previous prime is 15661561542521. The next prime is 15661561542551. The reversal of 15661561542543 is 34524516516651.

15661561542543 is a `hidden beast` number, since 1 + 5 + 6 + 6 + 1 + 56 + 1 + 5 + 42 + 543 = 666.

It is not a de Polignac number, because 15661561542543 - 2⁵ = 15661561542511 is a prime.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

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 15661561542543.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15661561542043) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2365093 + ... + 6075918.

It is an arithmetic number, because the mean of its divisors is an integer number (828738558160).

Almost surely, 2^{15661561542543} is an apocalyptic number.

15661561542543 is a deficient number, since it is larger than the sum of its proper divisors (10858072318577).

15661561542543 is an equidigital number, since it uses as much as digits as its factorization.

15661561542543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8450844 (or 8450838 counting only the distinct ones).

The product of its digits is 12960000, while the sum is 54.

The spelling of 15661561542543 in words is "fifteen trillion, six hundred sixty-one billion, five hundred sixty-one million, five hundred forty-two thousand, five hundred forty-three".