817777680 has 80 divisors (see below), whose sum is σ = 2542884864. Its totient is φ = 217405440.

The previous prime is 817777661. The next prime is 817777687. The reversal of 817777680 is 86777718.

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

It is not an unprimeable number, because it can be changed into a prime (817777687) 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, 75825 + ... + 85935.

Almost surely, 2^817777680 is an apocalyptic number.

817777680 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 817777680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1271442432).

817777680 is an abundant number, since it is smaller than the sum of its proper divisors (1725107184).

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

817777680 is a wasteful number, since it uses less digits than its factorization.

817777680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10464 (or 10458 counting only the distinct ones).

The product of its (nonzero) digits is 921984, while the sum is 51.

The square root of 817777680 is about 28596.8124097774. The cubic root of 817777680 is about 935.1438405297.

The spelling of 817777680 in words is "eight hundred seventeen million, seven hundred seventy-seven thousand, six hundred eighty".