642019561 has 4 divisors (see below), whose sum is σ = 642073300. Its totient is φ = 641965824.

The previous prime is 642019513. The next prime is 642019589. The reversal of 642019561 is 165910246.

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.

It can be written as a sum of positive squares in 2 ways, for example, as 339259561 + 302760000 = 18419^2 + 17400^2 .

It is a cyclic number.

It is not a de Polignac number, because 642019561 - 2¹¹ = 642017513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642019361) 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, 25 + ... + 35833.

It is an arithmetic number, because the mean of its divisors is an integer number (160518325).

Almost surely, 2^642019561 is an apocalyptic number.

It is an amenable number.

642019561 is a deficient number, since it is larger than the sum of its proper divisors (53739).

642019561 is a wasteful number, since it uses less digits than its factorization.

642019561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53738.

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 642019561 is about 25338.1049212446. The cubic root of 642019561 is about 862.6793851067.

The spelling of 642019561 in words is "six hundred forty-two million, nineteen thousand, five hundred sixty-one".