642565561 has 4 divisors (see below), whose sum is σ = 700980624. Its totient is φ = 584150500.

The previous prime is 642565543. The next prime is 642565597. The reversal of 642565561 is 165565246.

642565561 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.

It is a cyclic number.

It is not a de Polignac number, because 642565561 - 2¹³ = 642557369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642565061) 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, 29207515 + ... + 29207536.

It is an arithmetic number, because the mean of its divisors is an integer number (175245156).

Almost surely, 2^642565561 is an apocalyptic number.

It is an amenable number.

642565561 is a deficient number, since it is larger than the sum of its proper divisors (58415063).

642565561 is a wasteful number, since it uses less digits than its factorization.

642565561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58415062.

The product of its digits is 216000, while the sum is 40.

The square root of 642565561 is about 25348.8769179228. The cubic root of 642565561 is about 862.9238685618.

The spelling of 642565561 in words is "six hundred forty-two million, five hundred sixty-five thousand, five hundred sixty-one".