684195840 has 240 divisors, whose sum is σ = 2453665500. Its totient is φ = 176160768.

The previous prime is 684195793. The next prime is 684195847. The reversal of 684195840 is 48591486.

684195840 is a `hidden beast` number, since 68 + 4 + 1 + 9 + 584 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 681836544 + 2359296 = 26112^2 + 1536^2 .

It is a tau number, because it is divible by the number of its divisors (240).

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

It is not an unprimeable number, because it can be changed into a prime (684195847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 23592946 + ... + 23592974.

Almost surely, 2^684195840 is an apocalyptic number.

684195840 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 684195840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1226832750).

684195840 is an abundant number, since it is smaller than the sum of its proper divisors (1769469660).

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

684195840 is an frugal number, since it uses more digits than its factorization.

684195840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78 (or 39 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The square root of 684195840 is about 26157.1374580630. The cubic root of 684195840 is about 881.1708931556.

It can be divided in two parts, 684195 and 840, that added together give a triangular number (685035 = T₁₁₇₀).

The spelling of 684195840 in words is "six hundred eighty-four million, one hundred ninety-five thousand, eight hundred forty".