691228128 has 48 divisors (see below), whose sum is σ = 1816045056. Its totient is φ = 230209920.

The previous prime is 691228123. The next prime is 691228163. The reversal of 691228128 is 821822196.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691228123) 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, 144625 + ... + 149327.

It is an arithmetic number, because the mean of its divisors is an integer number (37834272).

Almost surely, 2^691228128 is an apocalyptic number.

It is an amenable number.

691228128 is an abundant number, since it is smaller than the sum of its proper divisors (1124816928).

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

691228128 is a wasteful number, since it uses less digits than its factorization.

691228128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6247 (or 6239 counting only the distinct ones).

The product of its digits is 27648, while the sum is 39.

The square root of 691228128 is about 26291.2176971703. The cubic root of 691228128 is about 884.1795530802.

The spelling of 691228128 in words is "six hundred ninety-one million, two hundred twenty-eight thousand, one hundred twenty-eight".