816218640 has 160 divisors (see below), whose sum is σ = 2821069440. Its totient is φ = 216912384.

The previous prime is 816218639. The next prime is 816218653. The reversal of 816218640 is 46812618.

816218640 is a `hidden beast` number, since 8 + 1 + 6 + 2 + 1 + 8 + 640 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 816218595 and 816218604.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 956454 + ... + 957306.

It is an arithmetic number, because the mean of its divisors is an integer number (17631684).

Almost surely, 2^816218640 is an apocalyptic number.

816218640 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 816218640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1410534720).

816218640 is an abundant number, since it is smaller than the sum of its proper divisors (2004850800).

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

816218640 is a wasteful number, since it uses less digits than its factorization.

816218640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1318 (or 1306 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 816218640 is about 28569.5404233250. The cubic root of 816218640 is about 934.5491988351.

The spelling of 816218640 in words is "eight hundred sixteen million, two hundred eighteen thousand, six hundred forty".