638907 has 4 divisors (see below), whose sum is σ = 851880. Its totient is φ = 425936.

The previous prime is 638893. The next prime is 638923. The reversal of 638907 is 709836.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 638907 - 2¹⁰ = 637883 is a prime.

It is a super-4 number, since 4×638907⁴ (a number of 24 digits) contains 4444 as substring.

It is a D-number.

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

638907 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (638977) 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, 106482 + ... + 106487.

It is an arithmetic number, because the mean of its divisors is an integer number (212970).

2⁶³⁸⁹⁰⁷ is an apocalyptic number.

638907 is a deficient number, since it is larger than the sum of its proper divisors (212973).

638907 is a wasteful number, since it uses less digits than its factorization.

638907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212972.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 638907 is about 799.3165830883. The cubic root of 638907 is about 86.1283013740.

The spelling of 638907 in words is "six hundred thirty-eight thousand, nine hundred seven".