638984771 has 2 divisors, whose sum is σ = 638984772. Its totient is φ = 638984770.

The previous prime is 638984761. The next prime is 638984777. The reversal of 638984771 is 177489836.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638984771 is a prime.

It is not a weakly prime, because it can be changed into another prime (638984777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319492385 + 319492386.

It is an arithmetic number, because the mean of its divisors is an integer number (319492386).

Almost surely, 2^638984771 is an apocalyptic number.

638984771 is a deficient number, since it is larger than the sum of its proper divisors (1).

638984771 is an equidigital number, since it uses as much as digits as its factorization.

638984771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2032128, while the sum is 53.

The square root of 638984771 is about 25278.1480927698. The cubic root of 638984771 is about 861.3179589013.

The spelling of 638984771 in words is "six hundred thirty-eight million, nine hundred eighty-four thousand, seven hundred seventy-one".