638109 has 6 divisors (see below), whose sum is σ = 921726. Its totient is φ = 425400.

The previous prime is 638081. The next prime is 638117. The reversal of 638109 is 901836.

It can be written as a sum of positive squares in only one way, i.e., 632025 + 6084 = 795^2 + 78^2 .

It is not a de Polignac number, because 638109 - 2⁹ = 637597 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638159) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35442 + ... + 35459.

It is an arithmetic number, because the mean of its divisors is an integer number (153621).

2⁶³⁸¹⁰⁹ is an apocalyptic number.

It is an amenable number.

638109 is a deficient number, since it is larger than the sum of its proper divisors (283617).

638109 is a wasteful number, since it uses less digits than its factorization.

638109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70907 (or 70904 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 638109 is about 798.8172506900. The cubic root of 638109 is about 86.0924281200.

It can be divided in two parts, 638 and 109, that added together give a palindrome (747).

The spelling of 638109 in words is "six hundred thirty-eight thousand, one hundred nine".