817801920 has 336 divisors, whose sum is σ = 3145353120. Its totient is φ = 201056256.

The previous prime is 817801883. The next prime is 817801921. The reversal of 817801920 is 29108718.

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

It is not an unprimeable number, because it can be changed into a prime (817801921) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1010476 + ... + 1011284.

It is an arithmetic number, because the mean of its divisors is an integer number (9361170).

Almost surely, 2^817801920 is an apocalyptic number.

817801920 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 817801920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1572676560).

817801920 is an abundant number, since it is smaller than the sum of its proper divisors (2327551200).

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

817801920 is a wasteful number, since it uses less digits than its factorization.

817801920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 854 (or 832 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 817801920 is about 28597.2362300975. The cubic root of 817801920 is about 935.1530800673.

The spelling of 817801920 in words is "eight hundred seventeen million, eight hundred one thousand, nine hundred twenty".