638917 has 4 divisors (see below), whose sum is σ = 666720. Its totient is φ = 611116.

The previous prime is 638893. The next prime is 638923. The reversal of 638917 is 719836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638917 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638977) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 13867 + ... + 13912.

It is an arithmetic number, because the mean of its divisors is an integer number (166680).

2⁶³⁸⁹¹⁷ is an apocalyptic number.

It is an amenable number.

638917 is a deficient number, since it is larger than the sum of its proper divisors (27803).

638917 is a wasteful number, since it uses less digits than its factorization.

638917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27802.

The product of its digits is 9072, while the sum is 34.

The square root of 638917 is about 799.3228384076. The cubic root of 638917 is about 86.1287507240.

The spelling of 638917 in words is "six hundred thirty-eight thousand, nine hundred seventeen".