640954 has 4 divisors (see below), whose sum is σ = 961434. Its totient is φ = 320476.

The previous prime is 640949. The next prime is 640957. The reversal of 640954 is 459046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 332929 + 308025 = 577^2 + 555^2 .

It is not an unprimeable number, because it can be changed into a prime (640957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160237 + ... + 160240.

2⁶⁴⁰⁹⁵⁴ is an apocalyptic number.

640954 is a deficient number, since it is larger than the sum of its proper divisors (320480).

640954 is a wasteful number, since it uses less digits than its factorization.

640954 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320479.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 640954 is about 800.5960279692. The cubic root of 640954 is about 86.2201857325.

The spelling of 640954 in words is "six hundred forty thousand, nine hundred fifty-four".