640499999 has 2 divisors, whose sum is σ = 640500000. Its totient is φ = 640499998.

The previous prime is 640499987. The next prime is 640500011. The reversal of 640499999 is 999994046.

It is a balanced prime because it is at equal distance from previous prime (640499987) and next prime (640500011).

It is a cyclic number.

It is not a de Polignac number, because 640499999 - 2¹² = 640495903 is a prime.

It is a Chen prime.

640499999 is a modest number, since divided by 99999 gives 6404 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640499969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320249999 + 320250000.

It is an arithmetic number, because the mean of its divisors is an integer number (320250000).

Almost surely, 2^640499999 is an apocalyptic number.

640499999 is a deficient number, since it is larger than the sum of its proper divisors (1).

640499999 is an equidigital number, since it uses as much as digits as its factorization.

640499999 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5668704, while the sum is 59.

The square root of 640499999 is about 25308.1014499310. The cubic root of 640499999 is about 861.9982374269.

The spelling of 640499999 in words is "six hundred forty million, four hundred ninety-nine thousand, nine hundred ninety-nine".