638816769 has 12 divisors (see below), whose sum is σ = 977014116. Its totient is φ = 400826112.

The previous prime is 638816767. The next prime is 638816779. The reversal of 638816769 is 967618836.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 181926144 + 456890625 = 13488^2 + 21375^2 .

It is not a de Polignac number, because 638816769 - 2¹ = 638816767 is a prime.

It is a super-2 number, since 2×638816769² = 816173728711198722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (638816767) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2087484 + ... + 2087789.

It is an arithmetic number, because the mean of its divisors is an integer number (81417843).

Almost surely, 2^638816769 is an apocalyptic number.

It is an amenable number.

638816769 is a deficient number, since it is larger than the sum of its proper divisors (338197347).

638816769 is a wasteful number, since it uses less digits than its factorization.

638816769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4175296 (or 4175293 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 54.

The square root of 638816769 is about 25274.8248065145. The cubic root of 638816769 is about 861.2424663231.

The spelling of 638816769 in words is "six hundred thirty-eight million, eight hundred sixteen thousand, seven hundred sixty-nine".