691521216 has 112 divisors (see below), whose sum is σ = 1900781568. Its totient is φ = 221644800.

The previous prime is 691521203. The next prime is 691521217. The reversal of 691521216 is 612125196.

It is not an unprimeable number, because it can be changed into a prime (691521217) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1327036 + ... + 1327556.

It is an arithmetic number, because the mean of its divisors is an integer number (16971264).

Almost surely, 2^691521216 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 691521216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (950390784).

691521216 is an abundant number, since it is smaller than the sum of its proper divisors (1209260352).

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

691521216 is a wasteful number, since it uses less digits than its factorization.

691521216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 790 (or 780 counting only the distinct ones).

The product of its digits is 6480, while the sum is 33.

The square root of 691521216 is about 26296.7909829317. The cubic root of 691521216 is about 884.3045025668.

The spelling of 691521216 in words is "six hundred ninety-one million, five hundred twenty-one thousand, two hundred sixteen".