816217920 has 168 divisors, whose sum is σ = 3208593024. Its totient is φ = 186559488.

The previous prime is 816217907. The next prime is 816217921. The reversal of 816217920 is 29712618.

816217920 is a `hidden beast` number, since 8 + 1 + 621 + 7 + 9 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (168).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816217921) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 84 + ... + 40403.

It is an arithmetic number, because the mean of its divisors is an integer number (19098768).

Almost surely, 2^816217920 is an apocalyptic number.

816217920 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 816217920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1604296512).

816217920 is an abundant number, since it is smaller than the sum of its proper divisors (2392375104).

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

816217920 is a wasteful number, since it uses less digits than its factorization.

816217920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40517 (or 40504 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

The square root of 816217920 is about 28569.5278224895. The cubic root of 816217920 is about 934.5489240412.

The spelling of 816217920 in words is "eight hundred sixteen million, two hundred seventeen thousand, nine hundred twenty".