639346993 has 2 divisors, whose sum is σ = 639346994. Its totient is φ = 639346992.

The previous prime is 639346957. The next prime is 639346997. The reversal of 639346993 is 399643936.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 609447969 + 29899024 = 24687^2 + 5468^2 .

It is a cyclic number.

It is not a de Polignac number, because 639346993 - 2¹³ = 639338801 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 639346993.

It is not a weakly prime, because it can be changed into another prime (639346997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319673496 + 319673497.

It is an arithmetic number, because the mean of its divisors is an integer number (319673497).

Almost surely, 2^639346993 is an apocalyptic number.

It is an amenable number.

639346993 is a deficient number, since it is larger than the sum of its proper divisors (1).

639346993 is an equidigital number, since it uses as much as digits as its factorization.

639346993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2834352, while the sum is 52.

The square root of 639346993 is about 25285.3118034957. The cubic root of 639346993 is about 861.4806802441.

The spelling of 639346993 in words is "six hundred thirty-nine million, three hundred forty-six thousand, nine hundred ninety-three".