646809408 has 168 divisors, whose sum is σ = 2212238400. Its totient is φ = 184778496.

The previous prime is 646809407. The next prime is 646809433. The reversal of 646809408 is 804908646.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (168).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646809407) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 80853 + ... + 88491.

Almost surely, 2^646809408 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646809408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1106119200).

646809408 is an abundant number, since it is smaller than the sum of its proper divisors (1565428992).

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

646809408 is a wasteful number, since it uses less digits than its factorization.

646809408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7674 (or 7651 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 45.

The square root of 646809408 is about 25432.4479356589. The cubic root of 646809408 is about 864.8194386281.

It can be divided in two parts, 64680 and 9408, that added together give a cube (74088 = 42³).

The spelling of 646809408 in words is "six hundred forty-six million, eight hundred nine thousand, four hundred eight".