816691680 has 384 divisors, whose sum is σ = 3309465600. Its totient is φ = 184246272.

The previous prime is 816691657. The next prime is 816691691. The reversal of 816691680 is 86196618.

It is a happy number.

816691680 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 (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3417001 + ... + 3417239.

It is an arithmetic number, because the mean of its divisors is an integer number (8618400).

Almost surely, 2^816691680 is an apocalyptic number.

816691680 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 816691680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1654732800).

816691680 is an abundant number, since it is smaller than the sum of its proper divisors (2492773920).

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

816691680 is a wasteful number, since it uses less digits than its factorization.

816691680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 383 (or 369 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 816691680 is about 28577.8179712868. The cubic root of 816691680 is about 934.7297034844.

The spelling of 816691680 in words is "eight hundred sixteen million, six hundred ninety-one thousand, six hundred eighty".