1680817997 has 2 divisors, whose sum is σ = 1680817998. Its totient is φ = 1680817996.

The previous prime is 1680817993. The next prime is 1680818011. The reversal of 1680817997 is 7997180861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1436864836 + 243953161 = 37906^2 + 15619^2 .

It is a cyclic number.

It is not a de Polignac number, because 1680817997 - 2² = 1680817993 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1680817993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 840408998 + 840408999.

It is an arithmetic number, because the mean of its divisors is an integer number (840408999).

Almost surely, 2^1680817997 is an apocalyptic number.

It is an amenable number.

1680817997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1680817997 is an equidigital number, since it uses as much as digits as its factorization.

1680817997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1524096, while the sum is 56.

The square root of 1680817997 is about 40997.7803911383. The cubic root of 1680817997 is about 1188.9773001325.

The spelling of 1680817997 in words is "one billion, six hundred eighty million, eight hundred seventeen thousand, nine hundred ninety-seven".