691111087 has 2 divisors, whose sum is σ = 691111088. Its totient is φ = 691111086.

The previous prime is 691111079. The next prime is 691111147. The reversal of 691111087 is 780111196.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 691111087 - 2³ = 691111079 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691112087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345555543 + 345555544.

It is an arithmetic number, because the mean of its divisors is an integer number (345555544).

Almost surely, 2^691111087 is an apocalyptic number.

691111087 is a deficient number, since it is larger than the sum of its proper divisors (1).

691111087 is an equidigital number, since it uses as much as digits as its factorization.

691111087 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 34.

The square root of 691111087 is about 26288.9917455957. The cubic root of 691111087 is about 884.1296462085.

The spelling of 691111087 in words is "six hundred ninety-one million, one hundred eleven thousand, eighty-seven".