638855401 has 4 divisors (see below), whose sum is σ = 645180804. Its totient is φ = 632530000.

The previous prime is 638855389. The next prime is 638855453. The reversal of 638855401 is 104558836.

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 380289001 + 258566400 = 19501^2 + 16080^2 .

It is a cyclic number.

It is not a de Polignac number, because 638855401 - 2⁵ = 638855369 is a prime.

It is a super-3 number, since 3×638855401³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638855101) 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, 3162550 + ... + 3162751.

It is an arithmetic number, because the mean of its divisors is an integer number (161295201).

Almost surely, 2^638855401 is an apocalyptic number.

It is an amenable number.

638855401 is a deficient number, since it is larger than the sum of its proper divisors (6325403).

638855401 is a wasteful number, since it uses less digits than its factorization.

638855401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6325402.

The product of its (nonzero) digits is 115200, while the sum is 40.

The square root of 638855401 is about 25275.5890336902. The cubic root of 638855401 is about 861.2598269863.

The spelling of 638855401 in words is "six hundred thirty-eight million, eight hundred fifty-five thousand, four hundred one".