638863257 has 4 divisors (see below), whose sum is σ = 851817680. Its totient is φ = 425908836.

The previous prime is 638863237. The next prime is 638863273. The reversal of 638863257 is 752368836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 638863257 - 2¹⁰ = 638862233 is a prime.

It is a super-2 number, since 2×638863257² = 816292522289296098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638863207) 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 in 3 ways as a sum of consecutive naturals, for example, 106477207 + ... + 106477212.

It is an arithmetic number, because the mean of its divisors is an integer number (212954420).

Almost surely, 2^638863257 is an apocalyptic number.

It is an amenable number.

638863257 is a deficient number, since it is larger than the sum of its proper divisors (212954423).

638863257 is a wasteful number, since it uses less digits than its factorization.

638863257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212954422.

The product of its digits is 1451520, while the sum is 48.

The square root of 638863257 is about 25275.7444400754. The cubic root of 638863257 is about 861.2633572737.

The spelling of 638863257 in words is "six hundred thirty-eight million, eight hundred sixty-three thousand, two hundred fifty-seven".