642636439 has 2 divisors, whose sum is σ = 642636440. Its totient is φ = 642636438.

The previous prime is 642636391. The next prime is 642636443. The reversal of 642636439 is 934636246.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642636439 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 642636395 and 642636404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642631439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321318219 + 321318220.

It is an arithmetic number, because the mean of its divisors is an integer number (321318220).

Almost surely, 2^642636439 is an apocalyptic number.

642636439 is a deficient number, since it is larger than the sum of its proper divisors (1).

642636439 is an equidigital number, since it uses as much as digits as its factorization.

642636439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 559872, while the sum is 43.

The square root of 642636439 is about 25350.2749294756. The cubic root of 642636439 is about 862.9555955807.

The spelling of 642636439 in words is "six hundred forty-two million, six hundred thirty-six thousand, four hundred thirty-nine".