681978559 has 2 divisors, whose sum is σ = 681978560. Its totient is φ = 681978558.

The previous prime is 681978509. The next prime is 681978569. The reversal of 681978559 is 955879186.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 681978559 - 2¹¹ = 681976511 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681978509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340989279 + 340989280.

It is an arithmetic number, because the mean of its divisors is an integer number (340989280).

Almost surely, 2^681978559 is an apocalyptic number.

681978559 is a deficient number, since it is larger than the sum of its proper divisors (1).

681978559 is an equidigital number, since it uses as much as digits as its factorization.

681978559 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5443200, while the sum is 58.

The square root of 681978559 is about 26114.7192020133. The cubic root of 681978559 is about 880.2179896428.

The spelling of 681978559 in words is "six hundred eighty-one million, nine hundred seventy-eight thousand, five hundred fifty-nine".