638775 has 36 divisors (see below), whose sum is σ = 1218672. Its totient is φ = 318720.

The previous prime is 638767. The next prime is 638801. The reversal of 638775 is 577836.

It is not a de Polignac number, because 638775 - 2³ = 638767 is a prime.

It is a nialpdrome in base 15.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3742 + ... + 3908.

It is an arithmetic number, because the mean of its divisors is an integer number (33852).

2⁶³⁸⁷⁷⁵ is an apocalyptic number.

638775 is a deficient number, since it is larger than the sum of its proper divisors (579897).

638775 is a wasteful number, since it uses less digits than its factorization.

638775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 200 (or 192 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 638775 is about 799.2340082854. The cubic root of 638775 is about 86.1223695150.

It can be divided in two parts, 6 and 38775, that added together give a triangular number (38781 = T₂₇₈).

The spelling of 638775 in words is "six hundred thirty-eight thousand, seven hundred seventy-five".