642609139 has 2 divisors, whose sum is σ = 642609140. Its totient is φ = 642609138.

The previous prime is 642609119. The next prime is 642609161. The reversal of 642609139 is 931906246.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 642609139 - 2⁹ = 642608627 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (642609109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321304569 + 321304570.

It is an arithmetic number, because the mean of its divisors is an integer number (321304570).

Almost surely, 2^642609139 is an apocalyptic number.

642609139 is a deficient number, since it is larger than the sum of its proper divisors (1).

642609139 is an equidigital number, since it uses as much as digits as its factorization.

642609139 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69984, while the sum is 40.

The square root of 642609139 is about 25349.7364680582. The cubic root of 642609139 is about 862.9433755966.

The spelling of 642609139 in words is "six hundred forty-two million, six hundred nine thousand, one hundred thirty-nine".