638861371 has 2 divisors, whose sum is σ = 638861372. Its totient is φ = 638861370.

The previous prime is 638861291. The next prime is 638861383. The reversal of 638861371 is 173168836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638861371 - 2¹⁹ = 638337083 is a prime.

It is not a weakly prime, because it can be changed into another prime (638861771) 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, 319430685 + 319430686.

It is an arithmetic number, because the mean of its divisors is an integer number (319430686).

Almost surely, 2^638861371 is an apocalyptic number.

638861371 is a deficient number, since it is larger than the sum of its proper divisors (1).

638861371 is an equidigital number, since it uses as much as digits as its factorization.

638861371 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 43.

The square root of 638861371 is about 25275.7071315522. The cubic root of 638861371 is about 861.2625097557.

The spelling of 638861371 in words is "six hundred thirty-eight million, eight hundred sixty-one thousand, three hundred seventy-one".