731681 has 2 divisors, whose sum is σ = 731682. Its totient is φ = 731680.

The previous prime is 731651. The next prime is 731683. The reversal of 731681 is 186137.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 390625 + 341056 = 625^2 + 584^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-731681 is a prime.

It is a super-2 number, since 2×731681² = 1070714171522, which contains 22 as substring.

Together with 731683, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 731681.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 731681.

It is not a weakly prime, because it can be changed into another prime (731683) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 365840 + 365841.

It is an arithmetic number, because the mean of its divisors is an integer number (365841).

2⁷³¹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

731681 is a deficient number, since it is larger than the sum of its proper divisors (1).

731681 is an equidigital number, since it uses as much as digits as its factorization.

731681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 26.

The square root of 731681 is about 855.3835397060. The cubic root of 731681 is about 90.1101942434.

The spelling of 731681 in words is "seven hundred thirty-one thousand, six hundred eighty-one".