691217128069 has 8 divisors (see below), whose sum is σ = 756590753912. Its totient is φ = 627586799040.

The previous prime is 691217128061. The next prime is 691217128079. The reversal of 691217128069 is 960821712196.

It can be written as a sum of positive squares in 4 ways, for example, as 53236332900 + 637980795169 = 230730^2 + 798737^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 691217128069 - 2³ = 691217128061 is a prime.

It is a super-2 number, since 2×691217128069² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691217128061) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 435823374 + ... + 435824959.

It is an arithmetic number, because the mean of its divisors is an integer number (94573844239).

Almost surely, 2^691217128069 is an apocalyptic number.

It is an amenable number.

691217128069 is a deficient number, since it is larger than the sum of its proper divisors (65373625843).

691217128069 is a wasteful number, since it uses less digits than its factorization.

691217128069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 871648407.

The product of its (nonzero) digits is 653184, while the sum is 52.

The spelling of 691217128069 in words is "six hundred ninety-one billion, two hundred seventeen million, one hundred twenty-eight thousand, sixty-nine".