678133681 has 3 divisors (see below), whose sum is σ = 678159723.
Its totient is φ = 678107640.
The previous prime is 678133591. The next prime is 678133699. The reversal of 678133681 is 186331876.
The square root of 678133681 is 26041.
It is a perfect power (a square), and thus also a powerful number.
It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.
It can be written as a sum of positive squares in only one way, i.e., 632975281 + 45158400 = 25159^2 + 6720^2
It is not a de Polignac number, because 678133681 - 211 = 678131633 is a prime.
It is a super-2 number, since 2×6781336812 = 919730578613219522, which contains 22 as substring.
It is a Duffinian number.
It is not an unprimeable number, because it can be changed into a prime (678133381) by changing a digit.
It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 13021 + ... + 39061.
It is an arithmetic number, because the mean of its divisors is an integer number (226053241).
Almost surely, 2678133681 is an apocalyptic number.
678133681 is the 26041-st square number.
678133681 is the 13920-th centered heptagonal number and also the 13021-st centered octagonal number.
It is an amenable number.
678133681 is a deficient number, since it is larger than the sum of its proper divisors (26042).
678133681 is an frugal number, since it uses more digits than its factorization.
678133681 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 52082 (or 26041 counting only the distinct ones).
The product of its digits is 145152, while the sum is 43.
The cubic root of 678133681 is about 878.5606986002.
The spelling of 678133681 in words is "six hundred seventy-eight million, one hundred thirty-three thousand, six hundred eighty-one".