638475280 has 40 divisors (see below), whose sum is σ = 1486416024. Its totient is φ = 255052800.

The previous prime is 638475269. The next prime is 638475289. The reversal of 638475280 is 82574836.

It can be written as a sum of positive squares in 4 ways, for example, as 7661824 + 630813456 = 2768^2 + 25116^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (638475289) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60820 + ... + 70540.

Almost surely, 2^638475280 is an apocalyptic number.

It is an amenable number.

638475280 is an abundant number, since it is smaller than the sum of its proper divisors (847940744).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638475280 is a wasteful number, since it uses less digits than its factorization.

638475280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10555 (or 10549 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 43.

The square root of 638475280 is about 25268.0683868000. The cubic root of 638475280 is about 861.0889756487.

The spelling of 638475280 in words is "six hundred thirty-eight million, four hundred seventy-five thousand, two hundred eighty".