638820315477 has 12 divisors (see below), whose sum is σ = 923155946284. Its totient is φ = 425688445440.

The previous prime is 638820315449. The next prime is 638820315479. The reversal of 638820315477 is 774513028836.

It is a happy number.

638820315477 is a `hidden beast` number, since 6 + 388 + 203 + 1 + 54 + 7 + 7 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 476257332996 + 162562982481 = 690114^2 + 403191^2 .

It is not a de Polignac number, because 638820315477 - 2²² = 638816121173 is a prime.

It is a super-2 number, since 2×638820315477² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638820315479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15959308 + ... + 15999285.

Almost surely, 2^638820315477 is an apocalyptic number.

It is an amenable number.

638820315477 is a deficient number, since it is larger than the sum of its proper divisors (284335630807).

638820315477 is a wasteful number, since it uses less digits than its factorization.

638820315477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31960820 (or 31960817 counting only the distinct ones).

The product of its (nonzero) digits is 6773760, while the sum is 54.

The spelling of 638820315477 in words is "six hundred thirty-eight billion, eight hundred twenty million, three hundred fifteen thousand, four hundred seventy-seven".