691128864 has 36 divisors (see below), whose sum is σ = 1965398526. Its totient is φ = 230376192.

The previous prime is 691128821. The next prime is 691128871. The reversal of 691128864 is 468821196.

It can be written as a sum of positive squares in only one way, i.e., 687488400 + 3640464 = 26220^2 + 1908^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1199589 + ... + 1200164.

Almost surely, 2^691128864 is an apocalyptic number.

It is an amenable number.

691128864 is an abundant number, since it is smaller than the sum of its proper divisors (1274269662).

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

691128864 is a wasteful number, since it uses less digits than its factorization.

691128864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2399769 (or 2399758 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The square root of 691128864 is about 26289.3298507208. The cubic root of 691128864 is about 884.1372267737.

The spelling of 691128864 in words is "six hundred ninety-one million, one hundred twenty-eight thousand, eight hundred sixty-four".