691981056 has 360 divisors, whose sum is σ = 2368374624. Its totient is φ = 199065600.

The previous prime is 691981051. The next prime is 691981057. The reversal of 691981056 is 650189196.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691981051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 4582581 + ... + 4582731.

Almost surely, 2^691981056 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 691981056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1184187312).

691981056 is an abundant number, since it is smaller than the sum of its proper divisors (1676393568).

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

691981056 is a wasteful number, since it uses less digits than its factorization.

691981056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209 (or 186 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 45.

The square root of 691981056 is about 26305.5328020552. The cubic root of 691981056 is about 884.5004707561.

The spelling of 691981056 in words is "six hundred ninety-one million, nine hundred eighty-one thousand, fifty-six".