646404340 has 12 divisors (see below), whose sum is σ = 1357449156. Its totient is φ = 258561728.

The previous prime is 646404329. The next prime is 646404347. The reversal of 646404340 is 43404646.

646404340 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 464316304 + 182088036 = 21548^2 + 13494^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646404347) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16160089 + ... + 16160128.

It is an arithmetic number, because the mean of its divisors is an integer number (113120763).

Almost surely, 2^646404340 is an apocalyptic number.

It is an amenable number.

646404340 is an abundant number, since it is smaller than the sum of its proper divisors (711044816).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

646404340 is a wasteful number, since it uses less digits than its factorization.

646404340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32320226 (or 32320224 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 31.

The square root of 646404340 is about 25424.4830822575. The cubic root of 646404340 is about 864.6388682625.

Adding to 646404340 its reverse (43404646), we get a palindrome (689808986).

The spelling of 646404340 in words is "six hundred forty-six million, four hundred four thousand, three hundred forty".