639830641 has 2 divisors, whose sum is σ = 639830642. Its totient is φ = 639830640.

The previous prime is 639830591. The next prime is 639830663. The reversal of 639830641 is 146038936.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 625200016 + 14630625 = 25004^2 + 3825^2 .

It is a cyclic number.

It is not a de Polignac number, because 639830641 - 2²⁹ = 102959729 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 639830594 and 639830603.

It is not a weakly prime, because it can be changed into another prime (639830671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319915320 + 319915321.

It is an arithmetic number, because the mean of its divisors is an integer number (319915321).

Almost surely, 2^639830641 is an apocalyptic number.

It is an amenable number.

639830641 is a deficient number, since it is larger than the sum of its proper divisors (1).

639830641 is an equidigital number, since it uses as much as digits as its factorization.

639830641 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93312, while the sum is 40.

The square root of 639830641 is about 25294.8738087384. The cubic root of 639830641 is about 861.6978541182.

The spelling of 639830641 in words is "six hundred thirty-nine million, eight hundred thirty thousand, six hundred forty-one".