684400640 has 336 divisors, whose sum is σ = 2151546624. Its totient is φ = 206438400.

The previous prime is 684400631. The next prime is 684400679. The reversal of 684400640 is 46004486.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 684400597 and 684400606.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22077425 + ... + 22077455.

Almost surely, 2^684400640 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 684400640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1075773312).

684400640 is an abundant number, since it is smaller than the sum of its proper divisors (1467145984).

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

684400640 is a wasteful number, since it uses less digits than its factorization.

684400640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87 (or 56 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 32.

The square root of 684400640 is about 26161.0519666163. The cubic root of 684400640 is about 881.2588045329.

The spelling of 684400640 in words is "six hundred eighty-four million, four hundred thousand, six hundred forty".