640079 has 4 divisors (see below), whose sum is σ = 698280. Its totient is φ = 581880.

The previous prime is 640069. The next prime is 640099. The reversal of 640079 is 970046.

640079 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 640079 - 2¹² = 635983 is a prime.

It is a super-2 number, since 2×640079² = 819402252482, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640009) 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, 29084 + ... + 29105.

It is an arithmetic number, because the mean of its divisors is an integer number (174570).

2⁶⁴⁰⁰⁷⁹ is an apocalyptic number.

640079 is a deficient number, since it is larger than the sum of its proper divisors (58201).

640079 is a wasteful number, since it uses less digits than its factorization.

640079 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58200.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 640079 is about 800.0493734764. The cubic root of 640079 is about 86.1809332958.

The spelling of 640079 in words is "six hundred forty thousand, seventy-nine".