646842840 has 128 divisors (see below), whose sum is σ = 2334528000. Its totient is φ = 140064768.

The previous prime is 646842839. The next prime is 646842881. The reversal of 646842840 is 48248646.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 646842792 and 646842801.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4305 + ... + 36224.

It is an arithmetic number, because the mean of its divisors is an integer number (18238500).

Almost surely, 2^646842840 is an apocalyptic number.

646842840 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 646842840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1167264000).

646842840 is an abundant number, since it is smaller than the sum of its proper divisors (1687685160).

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

646842840 is a wasteful number, since it uses less digits than its factorization.

646842840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40569 (or 40565 counting only the distinct ones).

The product of its (nonzero) digits is 294912, while the sum is 42.

The square root of 646842840 is about 25433.1051977536. The cubic root of 646842840 is about 864.8343385069.

The spelling of 646842840 in words is "six hundred forty-six million, eight hundred forty-two thousand, eight hundred forty".