639809293 has 2 divisors, whose sum is σ = 639809294. Its totient is φ = 639809292.

The previous prime is 639809273. The next prime is 639809321. The reversal of 639809293 is 392908936.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 595213609 + 44595684 = 24397^2 + 6678^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639809293 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639809243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319904646 + 319904647.

It is an arithmetic number, because the mean of its divisors is an integer number (319904647).

Almost surely, 2^639809293 is an apocalyptic number.

It is an amenable number.

639809293 is a deficient number, since it is larger than the sum of its proper divisors (1).

639809293 is an equidigital number, since it uses as much as digits as its factorization.

639809293 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 629856, while the sum is 49.

The square root of 639809293 is about 25294.4518224847. The cubic root of 639809293 is about 861.6882704725.

The spelling of 639809293 in words is "six hundred thirty-nine million, eight hundred nine thousand, two hundred ninety-three".