678138656 has 24 divisors (see below), whose sum is σ = 1437785244. Its totient is φ = 312986880.

The previous prime is 678138613. The next prime is 678138673. The reversal of 678138656 is 656831876.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 652291600 + 25847056 = 25540^2 + 5084^2 .

It is a super-2 number, since 2×678138656² = 919744073522972672, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 814655 + ... + 815486.

Almost surely, 2^678138656 is an apocalyptic number.

It is an amenable number.

678138656 is an abundant number, since it is smaller than the sum of its proper divisors (759646588).

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

678138656 is a wasteful number, since it uses less digits than its factorization.

678138656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1630164 (or 1630156 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 50.

The square root of 678138656 is about 26041.0955222702. The cubic root of 678138656 is about 878.5628470599.

The spelling of 678138656 in words is "six hundred seventy-eight million, one hundred thirty-eight thousand, six hundred fifty-six".