681557761 has 16 divisors (see below), whose sum is σ = 729831168. Its totient is φ = 634233600.

The previous prime is 681557743. The next prime is 681557771. The reversal of 681557761 is 167755186.

It is a cyclic number.

It is not a de Polignac number, because 681557761 - 2⁷ = 681557633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681557741) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1030771 + ... + 1031431.

It is an arithmetic number, because the mean of its divisors is an integer number (45614448).

Almost surely, 2^681557761 is an apocalyptic number.

It is an amenable number.

681557761 is a deficient number, since it is larger than the sum of its proper divisors (48273407).

681557761 is a wasteful number, since it uses less digits than its factorization.

681557761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1272.

The product of its digits is 352800, while the sum is 46.

The square root of 681557761 is about 26106.6612380825. The cubic root of 681557761 is about 880.0369134826.

The spelling of 681557761 in words is "six hundred eighty-one million, five hundred fifty-seven thousand, seven hundred sixty-one".