638768929 has 2 divisors, whose sum is σ = 638768930. Its totient is φ = 638768928.

The previous prime is 638768909. The next prime is 638768953. The reversal of 638768929 is 929867836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 567535329 + 71233600 = 23823^2 + 8440^2 .

It is a cyclic number.

It is not a de Polignac number, because 638768929 - 2²³ = 630380321 is a prime.

It is not a weakly prime, because it can be changed into another prime (638768909) 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, 319384464 + 319384465.

It is an arithmetic number, because the mean of its divisors is an integer number (319384465).

Almost surely, 2^638768929 is an apocalyptic number.

It is an amenable number.

638768929 is a deficient number, since it is larger than the sum of its proper divisors (1).

638768929 is an equidigital number, since it uses as much as digits as its factorization.

638768929 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7838208, while the sum is 58.

The square root of 638768929 is about 25273.8783925222. The cubic root of 638768929 is about 861.2209667476.

The spelling of 638768929 in words is "six hundred thirty-eight million, seven hundred sixty-eight thousand, nine hundred twenty-nine".