638915481 has 6 divisors (see below), whose sum is σ = 922877930. Its totient is φ = 425943648.

The previous prime is 638915467. The next prime is 638915513. The reversal of 638915481 is 184519836.

638915481 is a `hidden beast` number, since 638 + 9 + 1 + 5 + 4 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 607376025 + 31539456 = 24645^2 + 5616^2 .

It is not a de Polignac number, because 638915481 - 2⁵ = 638915449 is a prime.

It is a super-2 number, since 2×638915481² = 816425983722922722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638915441) 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 5 ways as a sum of consecutive naturals, for example, 35495296 + ... + 35495313.

Almost surely, 2^638915481 is an apocalyptic number.

It is an amenable number.

638915481 is a deficient number, since it is larger than the sum of its proper divisors (283962449).

638915481 is a wasteful number, since it uses less digits than its factorization.

638915481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70990615 (or 70990612 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The square root of 638915481 is about 25276.7775042627. Note that the first 3 decimals coincide. The cubic root of 638915481 is about 861.2868246806.

The spelling of 638915481 in words is "six hundred thirty-eight million, nine hundred fifteen thousand, four hundred eighty-one".