15661561542535 has 16 divisors (see below), whose sum is σ = 19821891621600. Its totient is φ = 11846495154816.

The previous prime is 15661561542521. The next prime is 15661561542551. The reversal of 15661561542535 is 53524516516651.

It is a cyclic number.

It is not a de Polignac number, because 15661561542535 - 2¹³ = 15661561534343 is a prime.

It is a super-2 number, since 2×15661561542535² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 161895204 + ... + 161991913.

It is an arithmetic number, because the mean of its divisors is an integer number (1238868226350).

Almost surely, 2^{15661561542535} is an apocalyptic number.

15661561542535 is a deficient number, since it is larger than the sum of its proper divisors (4160330079065).

15661561542535 is a wasteful number, since it uses less digits than its factorization.

15661561542535 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 323887650.

The product of its digits is 16200000, while the sum is 55.

The spelling of 15661561542535 in words is "fifteen trillion, six hundred sixty-one billion, five hundred sixty-one million, five hundred forty-two thousand, five hundred thirty-five".