681557743 has 2 divisors, whose sum is σ = 681557744. Its totient is φ = 681557742.

The previous prime is 681557741. The next prime is 681557771. The reversal of 681557743 is 347755186.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 681557743 - 2¹ = 681557741 is a prime.

Together with 681557741, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 681557693 and 681557702.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681557741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340778871 + 340778872.

It is an arithmetic number, because the mean of its divisors is an integer number (340778872).

Almost surely, 2^681557743 is an apocalyptic number.

681557743 is a deficient number, since it is larger than the sum of its proper divisors (1).

681557743 is an equidigital number, since it uses as much as digits as its factorization.

681557743 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 705600, while the sum is 46.

The square root of 681557743 is about 26106.6608933429. The cubic root of 681557743 is about 880.0369057353.

The spelling of 681557743 in words is "six hundred eighty-one million, five hundred fifty-seven thousand, seven hundred forty-three".