638999 has 2 divisors, whose sum is σ = 639000. Its totient is φ = 638998.

The previous prime is 638993. The next prime is 639007. The reversal of 638999 is 999836.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 638999 - 2¹² = 634903 is a prime.

638999 is a modest number, since divided by 999 gives 638 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319499 + 319500.

It is an arithmetic number, because the mean of its divisors is an integer number (319500).

2⁶³⁸⁹⁹⁹ is an apocalyptic number.

638999 is a deficient number, since it is larger than the sum of its proper divisors (1).

638999 is an equidigital number, since it uses as much as digits as its factorization.

638999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 104976, while the sum is 44.

The square root of 638999 is about 799.3741301794. The cubic root of 638999 is about 86.1324352169.

The spelling of 638999 in words is "six hundred thirty-eight thousand, nine hundred ninety-nine".