680721757 has 2 divisors, whose sum is σ = 680721758. Its totient is φ = 680721756.

The previous prime is 680721737. The next prime is 680721773. The reversal of 680721757 is 757127086.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 487261476 + 193460281 = 22074^2 + 13909^2 .

It is a cyclic number.

It is not a de Polignac number, because 680721757 - 2²⁷ = 546504029 is a prime.

It is a super-2 number, since 2×680721757² = 926764220906334098, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (680721737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340360878 + 340360879.

It is an arithmetic number, because the mean of its divisors is an integer number (340360879).

Almost surely, 2^680721757 is an apocalyptic number.

It is an amenable number.

680721757 is a deficient number, since it is larger than the sum of its proper divisors (1).

680721757 is an equidigital number, since it uses as much as digits as its factorization.

680721757 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 164640, while the sum is 43.

The square root of 680721757 is about 26090.6450092749. The cubic root of 680721757 is about 879.6769462437.

The spelling of 680721757 in words is "six hundred eighty million, seven hundred twenty-one thousand, seven hundred fifty-seven".