640025 has 6 divisors (see below), whose sum is σ = 793662. Its totient is φ = 512000.

The previous prime is 640019. The next prime is 640027. The reversal of 640025 is 520046.

It can be written as a sum of positive squares in 3 ways, for example, as 226576 + 413449 = 476^2 + 643^2 .

It is not a de Polignac number, because 640025 - 2⁴ = 640009 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 639985 and 640012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640027) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12776 + ... + 12825.

It is an arithmetic number, because the mean of its divisors is an integer number (132277).

2⁶⁴⁰⁰²⁵ is an apocalyptic number.

It is an amenable number.

640025 is a deficient number, since it is larger than the sum of its proper divisors (153637).

640025 is a wasteful number, since it uses less digits than its factorization.

640025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25611 (or 25606 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 640025 is about 800.0156248474. The cubic root of 640025 is about 86.1785096881.

It can be divided in two parts, 6400 and 25, that multiplied together give a 4-th power (160000 = 20⁴).

The spelling of 640025 in words is "six hundred forty thousand, twenty-five".