640425 has 12 divisors (see below), whose sum is σ = 1058960. Its totient is φ = 341520.

The previous prime is 640421. The next prime is 640457. The reversal of 640425 is 524046.

It is a happy number.

640425 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 640425 - 2² = 640421 is a prime.

It is an Ulam number.

640425 is a lucky number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640425.

It is not an unprimeable number, because it can be changed into a prime (640421) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4195 + ... + 4344.

2⁶⁴⁰⁴²⁵ is an apocalyptic number.

It is an amenable number.

640425 is a deficient number, since it is larger than the sum of its proper divisors (418535).

640425 is a wasteful number, since it uses less digits than its factorization.

640425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8552 (or 8547 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 640425 is about 800.2655809167. The cubic root of 640425 is about 86.1964591042.

The spelling of 640425 in words is "six hundred forty thousand, four hundred twenty-five".