638448647 has 4 divisors (see below), whose sum is σ = 638499576. Its totient is φ = 638397720.

The previous prime is 638448641. The next prime is 638448661. The reversal of 638448647 is 746844836.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 638448647 - 2¹⁶ = 638383111 is a prime.

It is a super-2 number, since 2×638448647² = 815233349712261218, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 638448595 and 638448604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638448641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7997 + ... + 36617.

It is an arithmetic number, because the mean of its divisors is an integer number (159624894).

Almost surely, 2^638448647 is an apocalyptic number.

638448647 is a deficient number, since it is larger than the sum of its proper divisors (50929).

638448647 is a wasteful number, since it uses less digits than its factorization.

638448647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50928.

The product of its digits is 3096576, while the sum is 50.

The square root of 638448647 is about 25267.5413722823. The cubic root of 638448647 is about 861.0770024879.

The spelling of 638448647 in words is "six hundred thirty-eight million, four hundred forty-eight thousand, six hundred forty-seven".