691291789 has 4 divisors (see below), whose sum is σ = 691366300. Its totient is φ = 691217280.

The previous prime is 691291787. The next prime is 691291817. The reversal of 691291789 is 987192196.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 203632900 + 487658889 = 14270^2 + 22083^2 .

It is a cyclic number.

It is not a de Polignac number, because 691291789 - 2¹ = 691291787 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691291787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20964 + ... + 42685.

It is an arithmetic number, because the mean of its divisors is an integer number (172841575).

Almost surely, 2^691291789 is an apocalyptic number.

It is an amenable number.

691291789 is a deficient number, since it is larger than the sum of its proper divisors (74511).

691291789 is a wasteful number, since it uses less digits than its factorization.

691291789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74510.

The product of its digits is 489888, while the sum is 52.

The square root of 691291789 is about 26292.4283587500. The cubic root of 691291789 is about 884.2066960857.

The spelling of 691291789 in words is "six hundred ninety-one million, two hundred ninety-one thousand, seven hundred eighty-nine".