638923 has 2 divisors, whose sum is σ = 638924. Its totient is φ = 638922.

The previous prime is 638893. The next prime is 638933. The reversal of 638923 is 329836.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638923 is a prime.

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

It is not a weakly prime, because it can be changed into another prime (638933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319461 + 319462.

It is an arithmetic number, because the mean of its divisors is an integer number (319462).

2⁶³⁸⁹²³ is an apocalyptic number.

638923 is a deficient number, since it is larger than the sum of its proper divisors (1).

638923 is an equidigital number, since it uses as much as digits as its factorization.

638923 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 31.

The square root of 638923 is about 799.3265915757. The cubic root of 638923 is about 86.1290203317.

The spelling of 638923 in words is "six hundred thirty-eight thousand, nine hundred twenty-three".