638539201 has 4 divisors (see below), whose sum is σ = 639536004. Its totient is φ = 637542400.

The previous prime is 638539189. The next prime is 638539217. The reversal of 638539201 is 102935836.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 332114176 + 306425025 = 18224^2 + 17505^2 .

It is a cyclic number.

It is not a de Polignac number, because 638539201 - 2⁹ = 638538689 is a prime.

It is a super-2 number, since 2×638539201² = 815464622427436802, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638539001) 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, 497440 + ... + 498721.

It is an arithmetic number, because the mean of its divisors is an integer number (159884001).

Almost surely, 2^638539201 is an apocalyptic number.

It is an amenable number.

638539201 is a deficient number, since it is larger than the sum of its proper divisors (996803).

638539201 is an equidigital number, since it uses as much as digits as its factorization.

638539201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 996802.

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 638539201 is about 25269.3332124138. Note that the first 3 decimals coincide. The cubic root of 638539201 is about 861.1177106853.

The spelling of 638539201 in words is "six hundred thirty-eight million, five hundred thirty-nine thousand, two hundred one".