638881 has 4 divisors (see below), whose sum is σ = 643264. Its totient is φ = 634500.

The previous prime is 638861. The next prime is 638893. The reversal of 638881 is 188836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 638881 - 2¹³ = 630689 is a prime.

It is a super-2 number, since 2×638881² = 816337864322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638801) 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, 1965 + ... + 2266.

It is an arithmetic number, because the mean of its divisors is an integer number (160816).

2⁶³⁸⁸⁸¹ is an apocalyptic number.

It is an amenable number.

638881 is a deficient number, since it is larger than the sum of its proper divisors (4383).

638881 is a wasteful number, since it uses less digits than its factorization.

638881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4382.

The product of its digits is 9216, while the sum is 34.

The square root of 638881 is about 799.3003190291. The cubic root of 638881 is about 86.1271330422.

The spelling of 638881 in words is "six hundred thirty-eight thousand, eight hundred eighty-one".