638066879 has 2 divisors, whose sum is σ = 638066880. Its totient is φ = 638066878.

The previous prime is 638066857. The next prime is 638066881. The reversal of 638066879 is 978660836.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638066879 is a prime.

Together with 638066881, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 638066879.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638066839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319033439 + 319033440.

It is an arithmetic number, because the mean of its divisors is an integer number (319033440).

Almost surely, 2^638066879 is an apocalyptic number.

638066879 is a deficient number, since it is larger than the sum of its proper divisors (1).

638066879 is an equidigital number, since it uses as much as digits as its factorization.

638066879 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2612736, while the sum is 53.

The square root of 638066879 is about 25259.9857284204. The cubic root of 638066879 is about 860.9053378383.

The spelling of 638066879 in words is "six hundred thirty-eight million, sixty-six thousand, eight hundred seventy-nine".