640197 has 16 divisors (see below), whose sum is σ = 960960. Its totient is φ = 421200.

The previous prime is 640193. The next prime is 640219. The reversal of 640197 is 791046.

640197 is a `hidden beast` number, since 640 + 19 + 7 = 666.

It is not a de Polignac number, because 640197 - 2² = 640193 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

640197 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 640197.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640193) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3447 + ... + 3627.

It is an arithmetic number, because the mean of its divisors is an integer number (60060).

2⁶⁴⁰¹⁹⁷ is an apocalyptic number.

It is an amenable number.

640197 is a deficient number, since it is larger than the sum of its proper divisors (320763).

640197 is a wasteful number, since it uses less digits than its factorization.

640197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321 (or 315 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 640197 is about 800.1231155266. The cubic root of 640197 is about 86.1862288532.

The spelling of 640197 in words is "six hundred forty thousand, one hundred ninety-seven".