6818781397 has 4 divisors (see below), whose sum is σ = 7053911820. Its totient is φ = 6583650976.

The previous prime is 6818781353. The next prime is 6818781407. The reversal of 6818781397 is 7931878186.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7931878186 = 2 ⋅3965939093.

It can be written as a sum of positive squares in 2 ways, for example, as 5259005361 + 1559776036 = 72519^2 + 39494^2 .

It is a cyclic number.

It is not a de Polignac number, because 6818781397 - 2⁷ = 6818781269 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6818781337) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 117565168 + ... + 117565225.

It is an arithmetic number, because the mean of its divisors is an integer number (1763477955).

Almost surely, 2^6818781397 is an apocalyptic number.

It is an amenable number.

6818781397 is a deficient number, since it is larger than the sum of its proper divisors (235130423).

6818781397 is a wasteful number, since it uses less digits than its factorization.

6818781397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 235130422.

The product of its digits is 4064256, while the sum is 58.

The square root of 6818781397 is about 82575.9129347051. The cubic root of 6818781397 is about 1896.2790887338.

The spelling of 6818781397 in words is "six billion, eight hundred eighteen million, seven hundred eighty-one thousand, three hundred ninety-seven".