640099 has 2 divisors, whose sum is σ = 640100. Its totient is φ = 640098.

The previous prime is 640069. The next prime is 640109. The reversal of 640099 is 990046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640099 - 2¹¹ = 638051 is a prime.

640099 is a modest number, since divided by 99 gives 64 as remainder.

It is not a weakly prime, because it can be changed into another prime (640009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320049 + 320050.

It is an arithmetic number, because the mean of its divisors is an integer number (320050).

2⁶⁴⁰⁰⁹⁹ is an apocalyptic number.

640099 is a deficient number, since it is larger than the sum of its proper divisors (1).

640099 is an equidigital number, since it uses as much as digits as its factorization.

640099 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 640099 is about 800.0618726074. The cubic root of 640099 is about 86.1818308937.

It can be divided in two parts, 64009 and 9, that multiplied together give a square (576081 = 759²).

The spelling of 640099 in words is "six hundred forty thousand, ninety-nine".