640544867 has 2 divisors, whose sum is σ = 640544868. Its totient is φ = 640544866.

The previous prime is 640544791. The next prime is 640544893. The reversal of 640544867 is 768445046.

640544867 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640544867 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (640540867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320272433 + 320272434.

It is an arithmetic number, because the mean of its divisors is an integer number (320272434).

Almost surely, 2^640544867 is an apocalyptic number.

640544867 is a deficient number, since it is larger than the sum of its proper divisors (1).

640544867 is an equidigital number, since it uses as much as digits as its factorization.

640544867 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 645120, while the sum is 44.

The square root of 640544867 is about 25308.9878699248. The cubic root of 640544867 is about 862.0183650532.

It can be divided in two parts, 64054 and 4867, that added together give a cube (68921 = 41³).

The spelling of 640544867 in words is "six hundred forty million, five hundred forty-four thousand, eight hundred sixty-seven".