640995 has 16 divisors (see below), whose sum is σ = 1036032. Its totient is φ = 338400.

The previous prime is 640993. The next prime is 641051. The reversal of 640995 is 599046.

It is a happy number.

It is not a de Polignac number, because 640995 - 2¹ = 640993 is a prime.

640995 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640993) 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, 2124 + ... + 2406.

It is an arithmetic number, because the mean of its divisors is an integer number (64752).

2⁶⁴⁰⁹⁹⁵ is an apocalyptic number.

640995 is a deficient number, since it is larger than the sum of its proper divisors (395037).

640995 is a wasteful number, since it uses less digits than its factorization.

640995 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442.

The product of its (nonzero) digits is 9720, while the sum is 33.

The square root of 640995 is about 800.6216334824. The cubic root of 640995 is about 86.2220241131. Note that the first 3 decimals are identical.

The spelling of 640995 in words is "six hundred forty thousand, nine hundred ninety-five".