639196709 has 2 divisors, whose sum is σ = 639196710. Its totient is φ = 639196708.

The previous prime is 639196699. The next prime is 639196711. The reversal of 639196709 is 907691936.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 418079809 + 221116900 = 20447^2 + 14870^2 .

It is a cyclic number.

It is not a de Polignac number, because 639196709 - 2¹² = 639192613 is a prime.

Together with 639196711, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639196609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319598354 + 319598355.

It is an arithmetic number, because the mean of its divisors is an integer number (319598355).

Almost surely, 2^639196709 is an apocalyptic number.

It is an amenable number.

639196709 is a deficient number, since it is larger than the sum of its proper divisors (1).

639196709 is an equidigital number, since it uses as much as digits as its factorization.

639196709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 551124, while the sum is 50.

The square root of 639196709 is about 25282.3398640237. The cubic root of 639196709 is about 861.4131754779.

The spelling of 639196709 in words is "six hundred thirty-nine million, one hundred ninety-six thousand, seven hundred nine".