681818957 has 2 divisors, whose sum is σ = 681818958. Its totient is φ = 681818956.

The previous prime is 681818953. The next prime is 681818987. The reversal of 681818957 is 759818186.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 569013316 + 112805641 = 23854^2 + 10621^2 .

It is a cyclic number.

It is not a de Polignac number, because 681818957 - 2² = 681818953 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 681818899 and 681818908.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681818953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340909478 + 340909479.

It is an arithmetic number, because the mean of its divisors is an integer number (340909479).

Almost surely, 2^681818957 is an apocalyptic number.

It is an amenable number.

681818957 is a deficient number, since it is larger than the sum of its proper divisors (1).

681818957 is an equidigital number, since it uses as much as digits as its factorization.

681818957 is an evil number, because the sum of its binary digits is even.

The product of its digits is 967680, while the sum is 53.

The square root of 681818957 is about 26111.6632369522. The cubic root of 681818957 is about 880.1493191007.

The spelling of 681818957 in words is "six hundred eighty-one million, eight hundred eighteen thousand, nine hundred fifty-seven".