638784 has 42 divisors (see below), whose sum is σ = 1832610. Its totient is φ = 212736.

The previous prime is 638767. The next prime is 638801. The reversal of 638784 is 487836.

638784 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (638767) and next prime (638801).

It can be written as a sum of positive squares in only one way, i.e., 360000 + 278784 = 600^2 + 528^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

638784 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 22 + ... + 1130.

2⁶³⁸⁷⁸⁴ is an apocalyptic number.

638784 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (916305).

638784 is an abundant number, since it is smaller than the sum of its proper divisors (1193826).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638784 is a wasteful number, since it uses less digits than its factorization.

638784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1127 (or 1114 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 638784 is about 799.2396386566. The cubic root of 638784 is about 86.1227739859.

The spelling of 638784 in words is "six hundred thirty-eight thousand, seven hundred eighty-four".