639067993 has 2 divisors, whose sum is σ = 639067994. Its totient is φ = 639067992.

The previous prime is 639067967. The next prime is 639068009. The reversal of 639067993 is 399760936.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 611473984 + 27594009 = 24728^2 + 5253^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639067993 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 639067993.

It is not a weakly prime, because it can be changed into another prime (639067963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319533996 + 319533997.

It is an arithmetic number, because the mean of its divisors is an integer number (319533997).

Almost surely, 2^639067993 is an apocalyptic number.

It is an amenable number.

639067993 is a deficient number, since it is larger than the sum of its proper divisors (1).

639067993 is an equidigital number, since it uses as much as digits as its factorization.

639067993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1653372, while the sum is 52.

The square root of 639067993 is about 25279.7941645101. The cubic root of 639067993 is about 861.3553502419.

The spelling of 639067993 in words is "six hundred thirty-nine million, sixty-seven thousand, nine hundred ninety-three".