640009379 has 2 divisors, whose sum is σ = 640009380. Its totient is φ = 640009378.

The previous prime is 640009351. The next prime is 640009399. The reversal of 640009379 is 973900046.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640009379 is a prime.

It is a super-2 number, since 2×640009379² = 819224010415931282, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (640009399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320004689 + 320004690.

It is an arithmetic number, because the mean of its divisors is an integer number (320004690).

Almost surely, 2^640009379 is an apocalyptic number.

640009379 is a deficient number, since it is larger than the sum of its proper divisors (1).

640009379 is an equidigital number, since it uses as much as digits as its factorization.

640009379 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40824, while the sum is 38.

The square root of 640009379 is about 25298.4066494315. The cubic root of 640009379 is about 861.7780856678.

The spelling of 640009379 in words is "six hundred forty million, nine thousand, three hundred seventy-nine".