642844387 has 2 divisors, whose sum is σ = 642844388. Its totient is φ = 642844386.

The previous prime is 642844369. The next prime is 642844393. The reversal of 642844387 is 783448246.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642844387 is a prime.

It is not a weakly prime, because it can be changed into another prime (642844087) 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 as a sum of consecutive naturals, namely, 321422193 + 321422194.

It is an arithmetic number, because the mean of its divisors is an integer number (321422194).

Almost surely, 2^642844387 is an apocalyptic number.

642844387 is a deficient number, since it is larger than the sum of its proper divisors (1).

642844387 is an equidigital number, since it uses as much as digits as its factorization.

642844387 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1032192, while the sum is 46.

The square root of 642844387 is about 25354.3760917125. The cubic root of 642844387 is about 863.0486655899.

The spelling of 642844387 in words is "six hundred forty-two million, eight hundred forty-four thousand, three hundred eighty-seven".