15642564561 has 20 divisors (see below), whose sum is σ = 25164773172. Its totient is φ = 9626192928.

The previous prime is 15642564551. The next prime is 15642564563. The reversal of 15642564561 is 16546524651.

15642564561 is a `hidden beast` number, since 1 + 5 + 6 + 4 + 25 + 64 + 561 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 4335432336 + 11307132225 = 65844^2 + 106335^2 .

It is not a de Polignac number, because 15642564561 - 2⁵ = 15642564529 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (15642564563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 7426566 + ... + 7428671.

Almost surely, 2^15642564561 is an apocalyptic number.

It is an amenable number.

15642564561 is a deficient number, since it is larger than the sum of its proper divisors (9522208611).

15642564561 is a wasteful number, since it uses less digits than its factorization.

15642564561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14855262 (or 14855253 counting only the distinct ones).

The product of its digits is 864000, while the sum is 45.

The spelling of 15642564561 in words is "fifteen billion, six hundred forty-two million, five hundred sixty-four thousand, five hundred sixty-one".