681668153 has 2 divisors, whose sum is σ = 681668154. Its totient is φ = 681668152.

The previous prime is 681668137. The next prime is 681668191. The reversal of 681668153 is 351866186.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 673298704 + 8369449 = 25948^2 + 2893^2 .

It is a cyclic number.

It is not a de Polignac number, because 681668153 - 2⁴ = 681668137 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (681662153) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340834076 + 340834077.

It is an arithmetic number, because the mean of its divisors is an integer number (340834077).

Almost surely, 2^681668153 is an apocalyptic number.

It is an amenable number.

681668153 is a deficient number, since it is larger than the sum of its proper divisors (1).

681668153 is an equidigital number, since it uses as much as digits as its factorization.

681668153 is an evil number, because the sum of its binary digits is even.

The product of its digits is 207360, while the sum is 44.

The square root of 681668153 is about 26108.7754021517. The cubic root of 681668153 is about 880.0844241490.

The spelling of 681668153 in words is "six hundred eighty-one million, six hundred sixty-eight thousand, one hundred fifty-three".