640300391 has 4 divisors (see below), whose sum is σ = 651153000. Its totient is φ = 629447784.

The previous prime is 640300387. The next prime is 640300421. The reversal of 640300391 is 193003046.

640300391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 640300391 - 2² = 640300387 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640300391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640300891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5426216 + ... + 5426333.

It is an arithmetic number, because the mean of its divisors is an integer number (162788250).

Almost surely, 2^640300391 is an apocalyptic number.

640300391 is a deficient number, since it is larger than the sum of its proper divisors (10852609).

640300391 is a wasteful number, since it uses less digits than its factorization.

640300391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10852608.

The product of its (nonzero) digits is 1944, while the sum is 26.

The square root of 640300391 is about 25304.1575832905. The cubic root of 640300391 is about 861.9086825888.

The spelling of 640300391 in words is "six hundred forty million, three hundred thousand, three hundred ninety-one".