728686681 has 2 divisors, whose sum is σ = 728686682. Its totient is φ = 728686680.

The previous prime is 728686603. The next prime is 728686711. The reversal of 728686681 is 186686827.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 500193225 + 228493456 = 22365^2 + 15116^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-728686681 is a prime.

It is a super-2 number, since 2×728686681² = 1061968558133591522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (728686381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 364343340 + 364343341.

It is an arithmetic number, because the mean of its divisors is an integer number (364343341).

Almost surely, 2^728686681 is an apocalyptic number.

It is an amenable number.

728686681 is a deficient number, since it is larger than the sum of its proper divisors (1).

728686681 is an equidigital number, since it uses as much as digits as its factorization.

728686681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1548288, while the sum is 52.

The square root of 728686681 is about 26994.1971727258. The cubic root of 728686681 is about 899.8710436633.

The spelling of 728686681 in words is "seven hundred twenty-eight million, six hundred eighty-six thousand, six hundred eighty-one".