646420840000 has 280 divisors, whose sum is σ = 1749964175960. Its totient is φ = 235395072000.

The previous prime is 646420839979. The next prime is 646420840001. The reversal of 646420840000 is 48024646.

It is a happy number.

It can be written as a sum of positive squares in 20 ways, for example, as 638874095616 + 7546744384 = 799296^2 + 86872^2 .

It is not an unprimeable number, because it can be changed into a prime (646420840001) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 37951486 + ... + 37968514.

It is an arithmetic number, because the mean of its divisors is an integer number (6249872057).

Almost surely, 2^646420840000 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 646420840000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (874982087980).

646420840000 is an abundant number, since it is smaller than the sum of its proper divisors (1103543335960).

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

646420840000 is a wasteful number, since it uses less digits than its factorization.

646420840000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17147 (or 17122 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 34.

Adding to 646420840000 its reverse (48024646), we get a palindrome (646468864646).

The spelling of 646420840000 in words is "six hundred forty-six billion, four hundred twenty million, eight hundred forty thousand".