646346721680442 has 128 divisors (see below), whose sum is σ = 1457006948985600. Its totient is φ = 212350905704448.

The previous prime is 646346721680437. The next prime is 646346721680497. The reversal of 646346721680442 is 244086127643646.

646346721680442 is a `hidden beast` number, since 6 + 4 + 6 + 3 + 46 + 72 + 1 + 6 + 80 + 442 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 646346721680442.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 39929980273 + ... + 39929996459.

It is an arithmetic number, because the mean of its divisors is an integer number (11382866788950).

Almost surely, 2^{646346721680442} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646346721680442, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (728503474492800).

646346721680442 is an abundant number, since it is smaller than the sum of its proper divisors (810660227305158).

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

646346721680442 is a wasteful number, since it uses less digits than its factorization.

646346721680442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22637 (or 22631 counting only the distinct ones).

The product of its (nonzero) digits is 222953472, while the sum is 63.

The spelling of 646346721680442 in words is "six hundred forty-six trillion, three hundred forty-six billion, seven hundred twenty-one million, six hundred eighty thousand, four hundred forty-two".