638653 has 4 divisors (see below), whose sum is σ = 641628. Its totient is φ = 635680.

The previous prime is 638633. The next prime is 638663. The reversal of 638653 is 356836.

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 158404 + 480249 = 398^2 + 693^2 .

It is a cyclic number.

It is not a de Polignac number, because 638653 - 2⁵ = 638621 is a prime.

It is a Duffinian number.

638653 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638633) 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, 1138 + ... + 1603.

It is an arithmetic number, because the mean of its divisors is an integer number (160407).

2⁶³⁸⁶⁵³ is an apocalyptic number.

It is an amenable number.

638653 is a deficient number, since it is larger than the sum of its proper divisors (2975).

638653 is a wasteful number, since it uses less digits than its factorization.

638653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2974.

The product of its digits is 12960, while the sum is 31.

The square root of 638653 is about 799.1576815623. The cubic root of 638653 is about 86.1168863125.

It can be divided in two parts, 638 and 653, that multiplied together give a palindrome (416614).

The spelling of 638653 in words is "six hundred thirty-eight thousand, six hundred fifty-three".