691082681 has 2 divisors, whose sum is σ = 691082682. Its totient is φ = 691082680.

The previous prime is 691082671. The next prime is 691082701. The reversal of 691082681 is 186280196.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 461863081 + 229219600 = 21491^2 + 15140^2 .

It is a cyclic number.

It is not a de Polignac number, because 691082681 - 2⁶ = 691082617 is a prime.

It is a super-2 number, since 2×691082681² = 955190543956295522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (691082641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345541340 + 345541341.

It is an arithmetic number, because the mean of its divisors is an integer number (345541341).

Almost surely, 2^691082681 is an apocalyptic number.

It is an amenable number.

691082681 is a deficient number, since it is larger than the sum of its proper divisors (1).

691082681 is an equidigital number, since it uses as much as digits as its factorization.

691082681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 41472, while the sum is 41.

The square root of 691082681 is about 26288.4514758858. The cubic root of 691082681 is about 884.1175328974.

The spelling of 691082681 in words is "six hundred ninety-one million, eighty-two thousand, six hundred eighty-one".