640407 has 16 divisors (see below), whose sum is σ = 937440. Its totient is φ = 387072.

The previous prime is 640369. The next prime is 640411. The reversal of 640407 is 704046.

640407 is nontrivially palindromic in base 7.

It is not a de Polignac number, because 640407 - 2⁷ = 640279 is a prime.

It is a super-3 number, since 3×640407³ = 787933319140497429, which contains 333 as substring. Note that it is a super-d number also for d = 2.

640407 is a lucky number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640407.

It is not an unprimeable number, because it can be changed into a prime (640457) 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 15 ways as a sum of consecutive naturals, for example, 1263 + ... + 1695.

It is an arithmetic number, because the mean of its divisors is an integer number (58590).

2⁶⁴⁰⁴⁰⁷ is an apocalyptic number.

640407 is a deficient number, since it is larger than the sum of its proper divisors (297033).

640407 is a wasteful number, since it uses less digits than its factorization.

640407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 482.

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 640407 is about 800.2543345712. The cubic root of 640407 is about 86.1956515411.

The spelling of 640407 in words is "six hundred forty thousand, four hundred seven".