691409087 has 2 divisors, whose sum is σ = 691409088. Its totient is φ = 691409086.

The previous prime is 691409063. The next prime is 691409099. The reversal of 691409087 is 780904196.

691409087 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 is a cyclic number.

It is not a de Polignac number, because 691409087 - 2¹⁰ = 691408063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691409987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345704543 + 345704544.

It is an arithmetic number, because the mean of its divisors is an integer number (345704544).

Almost surely, 2^691409087 is an apocalyptic number.

691409087 is a deficient number, since it is larger than the sum of its proper divisors (1).

691409087 is an equidigital number, since it uses as much as digits as its factorization.

691409087 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 691409087 is about 26294.6589063254. The cubic root of 691409087 is about 884.2567038215.

The spelling of 691409087 in words is "six hundred ninety-one million, four hundred nine thousand, eighty-seven".