64561561 has 4 divisors (see below), whose sum is σ = 66644224. Its totient is φ = 62478900.

The previous prime is 64561547. The next prime is 64561573. The reversal of 64561561 is 16516546.

It is a happy number.

64561561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16516546 = 2 ⋅8258273.

It is a cyclic number.

It is not a de Polignac number, because 64561561 - 2¹⁹ = 64037273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64561501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1041285 + ... + 1041346.

It is an arithmetic number, because the mean of its divisors is an integer number (16661056).

Almost surely, 2^64561561 is an apocalyptic number.

It is an amenable number.

64561561 is a deficient number, since it is larger than the sum of its proper divisors (2082663).

64561561 is a wasteful number, since it uses less digits than its factorization.

64561561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2082662.

The product of its digits is 21600, while the sum is 34.

The square root of 64561561 is about 8035.0209084980. The cubic root of 64561561 is about 401.1665135583.

The spelling of 64561561 in words is "sixty-four million, five hundred sixty-one thousand, five hundred sixty-one".