638431 has 2 divisors, whose sum is σ = 638432. Its totient is φ = 638430.

The previous prime is 638423. The next prime is 638437. The reversal of 638431 is 134836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638431 - 2³ = 638423 is a prime.

It is a super-2 number, since 2×638431² = 815188283522, which contains 22 as substring.

It is an Ulam number.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 638396 and 638405.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319215 + 319216.

It is an arithmetic number, because the mean of its divisors is an integer number (319216).

2⁶³⁸⁴³¹ is an apocalyptic number.

638431 is a deficient number, since it is larger than the sum of its proper divisors (1).

638431 is an equidigital number, since it uses as much as digits as its factorization.

638431 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 25.

The square root of 638431 is about 799.0187732463. The cubic root of 638431 is about 86.1069068900.

The spelling of 638431 in words is "six hundred thirty-eight thousand, four hundred thirty-one".