691216056 has 192 divisors, whose sum is σ = 2120152320. Its totient is φ = 202245120.

The previous prime is 691216037. The next prime is 691216069. The reversal of 691216056 is 650612196.

691216056 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 691216056.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1210251 + ... + 1210821.

It is an arithmetic number, because the mean of its divisors is an integer number (11042460).

Almost surely, 2^691216056 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 691216056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1060076160).

691216056 is an abundant number, since it is smaller than the sum of its proper divisors (1428936264).

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

691216056 is a wasteful number, since it uses less digits than its factorization.

691216056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 666 (or 659 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The square root of 691216056 is about 26290.9881138005. The cubic root of 691216056 is about 884.1744057792.

The spelling of 691216056 in words is "six hundred ninety-one million, two hundred sixteen thousand, fifty-six".