691289128 has 16 divisors (see below), whose sum is σ = 1298340000. Its totient is φ = 345065136.

The previous prime is 691289099. The next prime is 691289129. The reversal of 691289128 is 821982196.

It is not an unprimeable number, because it can be changed into a prime (691289129) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67338 + ... + 76921.

It is an arithmetic number, because the mean of its divisors is an integer number (81146250).

Almost surely, 2^691289128 is an apocalyptic number.

It is an amenable number.

691289128 is a deficient number, since it is larger than the sum of its proper divisors (607050872).

691289128 is a wasteful number, since it uses less digits than its factorization.

691289128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144864 (or 144860 counting only the distinct ones).

The product of its digits is 124416, while the sum is 46.

The square root of 691289128 is about 26292.3777547790. The cubic root of 691289128 is about 884.2055615542.

The spelling of 691289128 in words is "six hundred ninety-one million, two hundred eighty-nine thousand, one hundred twenty-eight".