691512643 has 2 divisors, whose sum is σ = 691512644. Its totient is φ = 691512642.

The previous prime is 691512637. The next prime is 691512649. The reversal of 691512643 is 346215196.

691512643 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (691512637) and next prime (691512649).

It is a cyclic number.

It is not a de Polignac number, because 691512643 - 2⁵ = 691512611 is a prime.

It is not a weakly prime, because it can be changed into another prime (691512649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345756321 + 345756322.

It is an arithmetic number, because the mean of its divisors is an integer number (345756322).

Almost surely, 2^691512643 is an apocalyptic number.

691512643 is a deficient number, since it is larger than the sum of its proper divisors (1).

691512643 is an equidigital number, since it uses as much as digits as its factorization.

691512643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 37.

The square root of 691512643 is about 26296.6279777465. The cubic root of 691512643 is about 884.3008482206.

The spelling of 691512643 in words is "six hundred ninety-one million, five hundred twelve thousand, six hundred forty-three".