638390429 has 2 divisors, whose sum is σ = 638390430. Its totient is φ = 638390428.

The previous prime is 638390413. The next prime is 638390447. The reversal of 638390429 is 924093836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 634788025 + 3602404 = 25195^2 + 1898^2 .

It is a cyclic number.

It is not a de Polignac number, because 638390429 - 2⁴ = 638390413 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 638390429.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638390479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319195214 + 319195215.

It is an arithmetic number, because the mean of its divisors is an integer number (319195215).

Almost surely, 2^638390429 is an apocalyptic number.

It is an amenable number.

638390429 is a deficient number, since it is larger than the sum of its proper divisors (1).

638390429 is an equidigital number, since it uses as much as digits as its factorization.

638390429 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 279936, while the sum is 44.

The square root of 638390429 is about 25266.3893146607. The cubic root of 638390429 is about 861.0508287802.

The spelling of 638390429 in words is "six hundred thirty-eight million, three hundred ninety thousand, four hundred twenty-nine".