640615 has 8 divisors (see below), whose sum is σ = 793728. Its totient is φ = 495840.

The previous prime is 640613. The next prime is 640621. The reversal of 640615 is 516046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 640615 - 2¹ = 640613 is a prime.

It is a Duffinian number.

640615 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1912 + ... + 2221.

It is an arithmetic number, because the mean of its divisors is an integer number (99216).

2⁶⁴⁰⁶¹⁵ is an apocalyptic number.

640615 is a deficient number, since it is larger than the sum of its proper divisors (153113).

640615 is a wasteful number, since it uses less digits than its factorization.

640615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4169.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 640615 is about 800.3842827043. The cubic root of 640615 is about 86.2049824587.

The spelling of 640615 in words is "six hundred forty thousand, six hundred fifteen".