642643999 has 2 divisors, whose sum is σ = 642644000. Its totient is φ = 642643998.

The previous prime is 642643961. The next prime is 642644029. The reversal of 642643999 is 999346246.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642643999 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (642641999) 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, 321321999 + 321322000.

It is an arithmetic number, because the mean of its divisors is an integer number (321322000).

Almost surely, 2^642643999 is an apocalyptic number.

642643999 is a deficient number, since it is larger than the sum of its proper divisors (1).

642643999 is an equidigital number, since it uses as much as digits as its factorization.

642643999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2519424, while the sum is 52.

The square root of 642643999 is about 25350.4240398460. The cubic root of 642643999 is about 862.9589795152.

The spelling of 642643999 in words is "six hundred forty-two million, six hundred forty-three thousand, nine hundred ninety-nine".