15561621205545 has 16 divisors (see below), whose sum is σ = 25198576990272. Its totient is φ = 8199536955840.

The previous prime is 15561621205523. The next prime is 15561621205597. The reversal of 15561621205545 is 54550212616551.

It is not a de Polignac number, because 15561621205545 - 2³⁶ = 15492901728809 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 15561621205494 and 15561621205503.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6249645826 + ... + 6249648315.

It is an arithmetic number, because the mean of its divisors is an integer number (1574911061892).

Almost surely, 2^{15561621205545} is an apocalyptic number.

15561621205545 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

15561621205545 is a deficient number, since it is larger than the sum of its proper divisors (9636955784727).

15561621205545 is a wasteful number, since it uses less digits than its factorization.

15561621205545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12499294232.

The product of its (nonzero) digits is 1800000, while the sum is 48.

The spelling of 15561621205545 in words is "fifteen trillion, five hundred sixty-one billion, six hundred twenty-one million, two hundred five thousand, five hundred forty-five".