691918128 has 120 divisors (see below), whose sum is σ = 2124435456. Its totient is φ = 208483200.

The previous prime is 691918121. The next prime is 691918133. The reversal of 691918128 is 821819196.

691918128 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (691918121) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 301401 + ... + 303687.

Almost surely, 2^691918128 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691918128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1062217728).

691918128 is an abundant number, since it is smaller than the sum of its proper divisors (1432517328).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

691918128 is a wasteful number, since it uses less digits than its factorization.

691918128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2503 (or 2494 counting only the distinct ones).

The product of its digits is 62208, while the sum is 45.

The square root of 691918128 is about 26304.3366766775. The cubic root of 691918128 is about 884.4736581084.

It can be divided in two parts, 691 and 918128, that added together give a palindrome (918819).

The spelling of 691918128 in words is "six hundred ninety-one million, nine hundred eighteen thousand, one hundred twenty-eight".