15604756561 has 3 divisors (see below), whose sum is σ = 15604881481. Its totient is φ = 15604631642.

The previous prime is 15604756543. The next prime is 15604756577. The reversal of 15604756561 is 16565740651.

The square root of 15604756561 is 124919.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 16565740651 = 269 ⋅61582679.

It is not a de Polignac number, because 15604756561 - 2³³ = 7014821969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15604756511) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 62460 + ... + 187378.

Almost surely, 2^15604756561 is an apocalyptic number.

15604756561 is the 124919-th square number.

15604756561 is the 62460-th centered octagonal number.

It is an amenable number.

15604756561 is a deficient number, since it is larger than the sum of its proper divisors (124920).

15604756561 is an frugal number, since it uses more digits than its factorization.

15604756561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249838 (or 124919 counting only the distinct ones).

The product of its (nonzero) digits is 756000, while the sum is 46.

The spelling of 15604756561 in words is "fifteen billion, six hundred four million, seven hundred fifty-six thousand, five hundred sixty-one".