691128816 has 80 divisors (see below), whose sum is σ = 2046607104. Its totient is φ = 196872192.

The previous prime is 691128797. The next prime is 691128821. The reversal of 691128816 is 618821196.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 115695 + ... + 121521.

Almost surely, 2^691128816 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 691128816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1023303552).

691128816 is an abundant number, since it is smaller than the sum of its proper divisors (1355478288).

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

691128816 is a wasteful number, since it uses less digits than its factorization.

691128816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6198 (or 6192 counting only the distinct ones).

The product of its digits is 41472, while the sum is 42.

The square root of 691128816 is about 26289.3289378029. The cubic root of 691128816 is about 884.1372063055.

The spelling of 691128816 in words is "six hundred ninety-one million, one hundred twenty-eight thousand, eight hundred sixteen".