642867591 has 4 divisors (see below), whose sum is σ = 857156792. Its totient is φ = 428578392.

The previous prime is 642867557. The next prime is 642867601. The reversal of 642867591 is 195768246.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 642867591 - 2⁹ = 642867079 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 642867591.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642867541) 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, 107144596 + ... + 107144601.

It is an arithmetic number, because the mean of its divisors is an integer number (214289198).

Almost surely, 2^642867591 is an apocalyptic number.

642867591 is a deficient number, since it is larger than the sum of its proper divisors (214289201).

642867591 is a wasteful number, since it uses less digits than its factorization.

642867591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214289200.

The product of its digits is 725760, while the sum is 48.

The square root of 642867591 is about 25354.8336811741. The cubic root of 642867591 is about 863.0590496169.

The spelling of 642867591 in words is "six hundred forty-two million, eight hundred sixty-seven thousand, five hundred ninety-one".