640467305 has 4 divisors (see below), whose sum is σ = 768560772. Its totient is φ = 512373840.

The previous prime is 640467281. The next prime is 640467307. The reversal of 640467305 is 503764046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 270405136 + 370062169 = 16444^2 + 19237^2 .

It is a de Polignac number, because none of the positive numbers 2^k-640467305 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640467307) 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 in 3 ways as a sum of consecutive naturals, for example, 64046726 + ... + 64046735.

It is an arithmetic number, because the mean of its divisors is an integer number (192140193).

Almost surely, 2^640467305 is an apocalyptic number.

It is an amenable number.

640467305 is a deficient number, since it is larger than the sum of its proper divisors (128093467).

640467305 is a wasteful number, since it uses less digits than its factorization.

640467305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128093466.

The product of its (nonzero) digits is 60480, while the sum is 35.

The square root of 640467305 is about 25307.4555220394. The cubic root of 640467305 is about 861.9835704220.

The spelling of 640467305 in words is "six hundred forty million, four hundred sixty-seven thousand, three hundred five".