15506555006561 has 4 divisors (see below), whose sum is σ = 15724957189824. Its totient is φ = 15288152823300.

The previous prime is 15506555006531. The next prime is 15506555006603. The reversal of 15506555006561 is 16560055560551.

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 15506555006561 - 2⁴² = 11108508495457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15506555006531) 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, 109201091525 + ... + 109201091666.

It is an arithmetic number, because the mean of its divisors is an integer number (3931239297456).

Almost surely, 2^{15506555006561} is an apocalyptic number.

It is an amenable number.

15506555006561 is a deficient number, since it is larger than the sum of its proper divisors (218402183263).

15506555006561 is an equidigital number, since it uses as much as digits as its factorization.

15506555006561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218402183262.

The product of its (nonzero) digits is 3375000, while the sum is 50.

The spelling of 15506555006561 in words is "fifteen trillion, five hundred six billion, five hundred fifty-five million, six thousand, five hundred sixty-one".