691587817901 has 2 divisors, whose sum is σ = 691587817902. Its totient is φ = 691587817900.

The previous prime is 691587817897. The next prime is 691587817931. The reversal of 691587817901 is 109718785196.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 474030873001 + 217556944900 = 688499^2 + 466430^2 .

It is a cyclic number.

It is not a de Polignac number, because 691587817901 - 2² = 691587817897 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691587817931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345793908950 + 345793908951.

It is an arithmetic number, because the mean of its divisors is an integer number (345793908951).

Almost surely, 2^691587817901 is an apocalyptic number.

It is an amenable number.

691587817901 is a deficient number, since it is larger than the sum of its proper divisors (1).

691587817901 is an equidigital number, since it uses as much as digits as its factorization.

691587817901 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7620480, while the sum is 62.

The spelling of 691587817901 in words is "six hundred ninety-one billion, five hundred eighty-seven million, eight hundred seventeen thousand, nine hundred one".