681670817 has 2 divisors, whose sum is σ = 681670818. Its totient is φ = 681670816.

The previous prime is 681670799. The next prime is 681670819. The reversal of 681670817 is 718076186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 669567376 + 12103441 = 25876^2 + 3479^2 .

It is a cyclic number.

It is not a de Polignac number, because 681670817 - 2¹⁴ = 681654433 is a prime.

Together with 681670819, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (681670819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340835408 + 340835409.

It is an arithmetic number, because the mean of its divisors is an integer number (340835409).

Almost surely, 2^681670817 is an apocalyptic number.

It is an amenable number.

681670817 is a deficient number, since it is larger than the sum of its proper divisors (1).

681670817 is an equidigital number, since it uses as much as digits as its factorization.

681670817 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 112896, while the sum is 44.

The square root of 681670817 is about 26108.8264194314. The cubic root of 681670817 is about 880.0855706217.

The spelling of 681670817 in words is "six hundred eighty-one million, six hundred seventy thousand, eight hundred seventeen".