638091 has 8 divisors (see below), whose sum is σ = 945360. Its totient is φ = 425376.

The previous prime is 638081. The next prime is 638117. The reversal of 638091 is 190836.

It is not a de Polignac number, because 638091 - 2⁵ = 638059 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 23633 = 638091 / (6 + 3 + 8 + 0 + 9 + 1).

It is not an unprimeable number, because it can be changed into a prime (638051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11790 + ... + 11843.

It is an arithmetic number, because the mean of its divisors is an integer number (118170).

2⁶³⁸⁰⁹¹ is an apocalyptic number.

638091 is a deficient number, since it is larger than the sum of its proper divisors (307269).

638091 is a wasteful number, since it uses less digits than its factorization.

638091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23642 (or 23636 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 638091 is about 798.8059839536. The cubic root of 638091 is about 86.0916186041.

The spelling of 638091 in words is "six hundred thirty-eight thousand, ninety-one".