642352561 has 4 divisors (see below), whose sum is σ = 642694500. Its totient is φ = 642010624.

The previous prime is 642352541. The next prime is 642352573. The reversal of 642352561 is 165253246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165253246 = 2 ⋅82626623.

It can be written as a sum of positive squares in 2 ways, for example, as 304711936 + 337640625 = 17456^2 + 18375^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642352561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642352541) 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, 168136 + ... + 171913.

It is an arithmetic number, because the mean of its divisors is an integer number (160673625).

Almost surely, 2^642352561 is an apocalyptic number.

It is an amenable number.

642352561 is a deficient number, since it is larger than the sum of its proper divisors (341939).

642352561 is a wasteful number, since it uses less digits than its factorization.

642352561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341938.

The product of its digits is 43200, while the sum is 34.

The square root of 642352561 is about 25344.6752001283. The cubic root of 642352561 is about 862.8285096297.

The spelling of 642352561 in words is "six hundred forty-two million, three hundred fifty-two thousand, five hundred sixty-one".