690611681 has 2 divisors, whose sum is σ = 690611682. Its totient is φ = 690611680.

The previous prime is 690611629. The next prime is 690611693. The reversal of 690611681 is 186116096.

690611681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 394221025 + 296390656 = 19855^2 + 17216^2 .

It is a cyclic number.

It is not a de Polignac number, because 690611681 - 2⁶ = 690611617 is a prime.

It is a super-2 number, since 2×690611681² = 953888987867291522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (690611611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345305840 + 345305841.

It is an arithmetic number, because the mean of its divisors is an integer number (345305841).

Almost surely, 2^690611681 is an apocalyptic number.

It is an amenable number.

690611681 is a deficient number, since it is larger than the sum of its proper divisors (1).

690611681 is an equidigital number, since it uses as much as digits as its factorization.

690611681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 38.

The square root of 690611681 is about 26279.4916427240. The cubic root of 690611681 is about 883.9166336383.

The spelling of 690611681 in words is "six hundred ninety million, six hundred eleven thousand, six hundred eighty-one".