640691459 has 2 divisors, whose sum is σ = 640691460. Its totient is φ = 640691458.

The previous prime is 640691437. The next prime is 640691483. The reversal of 640691459 is 954196046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640691459 - 2²⁴ = 623914243 is a prime.

It is not a weakly prime, because it can be changed into another prime (640697459) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320345729 + 320345730.

It is an arithmetic number, because the mean of its divisors is an integer number (320345730).

Almost surely, 2^640691459 is an apocalyptic number.

640691459 is a deficient number, since it is larger than the sum of its proper divisors (1).

640691459 is an equidigital number, since it uses as much as digits as its factorization.

640691459 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 233280, while the sum is 44.

The square root of 640691459 is about 25311.8837505232. The cubic root of 640691459 is about 862.0841191553.

The spelling of 640691459 in words is "six hundred forty million, six hundred ninety-one thousand, four hundred fifty-nine".