639946859 has 2 divisors, whose sum is σ = 639946860. Its totient is φ = 639946858.

The previous prime is 639946711. The next prime is 639946873. The reversal of 639946859 is 958649936.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 639946859 - 2²⁴ = 623169643 is a prime.

It is a super-3 number, since 3×639946859³ (a number of 27 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 639946798 and 639946807.

It is not a weakly prime, because it can be changed into another prime (639946889) 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, 319973429 + 319973430.

It is an arithmetic number, because the mean of its divisors is an integer number (319973430).

Almost surely, 2^639946859 is an apocalyptic number.

639946859 is a deficient number, since it is larger than the sum of its proper divisors (1).

639946859 is an equidigital number, since it uses as much as digits as its factorization.

639946859 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12597120, while the sum is 59.

The square root of 639946859 is about 25297.1709683119. The cubic root of 639946859 is about 861.7500235163.

The spelling of 639946859 in words is "six hundred thirty-nine million, nine hundred forty-six thousand, eight hundred fifty-nine".