640597 has 4 divisors (see below), whose sum is σ = 646380. Its totient is φ = 634816.

The previous prime is 640589. The next prime is 640613. The reversal of 640597 is 795046.

640597 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 can be written as a sum of positive squares in 2 ways, for example, as 64516 + 576081 = 254^2 + 759^2 .

It is a cyclic number.

It is not a de Polignac number, because 640597 - 2³ = 640589 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

640597 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644597) 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, 2722 + ... + 2947.

It is an arithmetic number, because the mean of its divisors is an integer number (161595).

2⁶⁴⁰⁵⁹⁷ is an apocalyptic number.

It is an amenable number.

640597 is a deficient number, since it is larger than the sum of its proper divisors (5783).

640597 is a wasteful number, since it uses less digits than its factorization.

640597 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5782.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 640597 is about 800.3730380266. The cubic root of 640597 is about 86.2041750552.

Subtracting 640597 from its reverse (795046), we obtain a square (154449 = 393²).

The spelling of 640597 in words is "six hundred forty thousand, five hundred ninety-seven".