638421 has 24 divisors (see below), whose sum is σ = 1023264. Its totient is φ = 352800.

The previous prime is 638371. The next prime is 638423. The reversal of 638421 is 124836.

It is a happy number.

It is not a de Polignac number, because 638421 - 2⁹ = 637909 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 638391 and 638400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638423) 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 23 ways as a sum of consecutive naturals, for example, 6271 + ... + 6371.

It is an arithmetic number, because the mean of its divisors is an integer number (42636).

2⁶³⁸⁴²¹ is an apocalyptic number.

It is an amenable number.

638421 is a deficient number, since it is larger than the sum of its proper divisors (384843).

638421 is a wasteful number, since it uses less digits than its factorization.

638421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161 (or 154 counting only the distinct ones).

The product of its digits is 1152, while the sum is 24.

The square root of 638421 is about 799.0125155465. The cubic root of 638421 is about 86.1064573120.

The spelling of 638421 in words is "six hundred thirty-eight thousand, four hundred twenty-one".