640946 has 16 divisors (see below), whose sum is σ = 1028160. Its totient is φ = 298800.

The previous prime is 640943. The next prime is 640949. The reversal of 640946 is 649046.

It is an interprime number because it is at equal distance from previous prime (640943) and next prime (640949).

It is not an unprimeable number, because it can be changed into a prime (640943) 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 7 ways as a sum of consecutive naturals, for example, 3755 + ... + 3921.

It is an arithmetic number, because the mean of its divisors is an integer number (64260).

2⁶⁴⁰⁹⁴⁶ is an apocalyptic number.

640946 is a deficient number, since it is larger than the sum of its proper divisors (387214).

640946 is a wasteful number, since it uses less digits than its factorization.

640946 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 640946 is about 800.5910316760. The cubic root of 640946 is about 86.2198270149.

Subtracting 640946 from its reverse (649046), we obtain a square (8100 = 90²).

The spelling of 640946 in words is "six hundred forty thousand, nine hundred forty-six".