638780 has 36 divisors (see below), whose sum is σ = 1447320. Its totient is φ = 236160.

The previous prime is 638767. The next prime is 638801. The reversal of 638780 is 87836.

It is a congruent number.

It is an unprimeable number.

638780 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15560 + ... + 15600.

2⁶³⁸⁷⁸⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (723660).

638780 is an abundant number, since it is smaller than the sum of its proper divisors (808540).

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

638780 is a wasteful number, since it uses less digits than its factorization.

638780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110 (or 67 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 638780 is about 799.2371362743. The cubic root of 638780 is about 86.1225942215.

The spelling of 638780 in words is "six hundred thirty-eight thousand, seven hundred eighty".