638390479 has 2 divisors, whose sum is σ = 638390480. Its totient is φ = 638390478.

The previous prime is 638390447. The next prime is 638390483. The reversal of 638390479 is 974093836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638390479 - 2⁵ = 638390447 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638390429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319195239 + 319195240.

It is an arithmetic number, because the mean of its divisors is an integer number (319195240).

Almost surely, 2^638390479 is an apocalyptic number.

638390479 is a deficient number, since it is larger than the sum of its proper divisors (1).

638390479 is an equidigital number, since it uses as much as digits as its factorization.

638390479 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 979776, while the sum is 49.

The square root of 638390479 is about 25266.3903041174. The cubic root of 638390479 is about 861.0508512599.

The spelling of 638390479 in words is "six hundred thirty-eight million, three hundred ninety thousand, four hundred seventy-nine".