646719840 has 288 divisors, whose sum is σ = 2402356320. Its totient is φ = 157483008.

The previous prime is 646719803. The next prime is 646719841. The reversal of 646719840 is 48917646.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646719841) 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 47 ways as a sum of consecutive naturals, for example, 3350784 + ... + 3350976.

It is an arithmetic number, because the mean of its divisors is an integer number (8341515).

Almost surely, 2^646719840 is an apocalyptic number.

646719840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646719840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1201178160).

646719840 is an abundant number, since it is smaller than the sum of its proper divisors (1755636480).

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

646719840 is a wasteful number, since it uses less digits than its factorization.

646719840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 406 (or 395 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The square root of 646719840 is about 25430.6869745982. The cubic root of 646719840 is about 864.7795176858.

The spelling of 646719840 in words is "six hundred forty-six million, seven hundred nineteen thousand, eight hundred forty".