678815640 has 112 divisors (see below), whose sum is σ = 2290053600. Its totient is φ = 181009728.

The previous prime is 678815609. The next prime is 678815651. The reversal of 678815640 is 46518876.

It is a happy number.

678815640 is a `hidden beast` number, since 6 + 7 + 8 + 81 + 564 + 0 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 17521 + ... + 40799.

Almost surely, 2^678815640 is an apocalyptic number.

678815640 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 678815640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1145026800).

678815640 is an abundant number, since it is smaller than the sum of its proper divisors (1611237960).

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

678815640 is a wasteful number, since it uses less digits than its factorization.

678815640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23308 (or 23289 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 45.

The square root of 678815640 is about 26054.0906577067. The cubic root of 678815640 is about 878.8551054719.

The spelling of 678815640 in words is "six hundred seventy-eight million, eight hundred fifteen thousand, six hundred forty".