691349680 has 80 divisors (see below), whose sum is σ = 1840507200. Its totient is φ = 236583936.

The previous prime is 691349677. The next prime is 691349689. The reversal of 691349680 is 86943196.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×691349680² = 955928760072204800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 691349680.

It is not an unprimeable number, because it can be changed into a prime (691349689) 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, 445546 + ... + 447094.

It is an arithmetic number, because the mean of its divisors is an integer number (23006340).

Almost surely, 2^691349680 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 691349680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (920253600).

691349680 is an abundant number, since it is smaller than the sum of its proper divisors (1149157520).

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

691349680 is a wasteful number, since it uses less digits than its factorization.

691349680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2366 (or 2360 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 46.

The square root of 691349680 is about 26293.5292420017. The cubic root of 691349680 is about 884.2313775019.

The spelling of 691349680 in words is "six hundred ninety-one million, three hundred forty-nine thousand, six hundred eighty".