691217128090 has 8 divisors (see below), whose sum is σ = 1244190830580. Its totient is φ = 276486851232.

The previous prime is 691217128079. The next prime is 691217128097. The reversal of 691217128090 is 90821712196.

It can be written as a sum of positive squares in 2 ways, for example, as 640331242849 + 50885885241 = 800207^2 + 225579^2 .

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

It is a super-2 number, since 2×691217128090² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 691217128090.

It is not an unprimeable number, because it can be changed into a prime (691217128097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34560856395 + ... + 34560856414.

Almost surely, 2^691217128090 is an apocalyptic number.

691217128090 is a deficient number, since it is larger than the sum of its proper divisors (552973702490).

691217128090 is a wasteful number, since it uses less digits than its factorization.

691217128090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69121712816.

The product of its (nonzero) digits is 108864, while the sum is 46.

The spelling of 691217128090 in words is "six hundred ninety-one billion, two hundred seventeen million, one hundred twenty-eight thousand, ninety".