818864640 has 400 divisors, whose sum is σ = 3208455360. Its totient is φ = 197959680.

The previous prime is 818864639. The next prime is 818864693. The reversal of 818864640 is 46468818.

818864640 is a `hidden beast` number, since 8 + 188 + 6 + 464 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2280781 + ... + 2281139.

Almost surely, 2^818864640 is an apocalyptic number.

818864640 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 818864640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1604227680).

818864640 is an abundant number, since it is smaller than the sum of its proper divisors (2389590720).

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

818864640 is a wasteful number, since it uses less digits than its factorization.

818864640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405 (or 380 counting only the distinct ones).

The product of its (nonzero) digits is 294912, while the sum is 45.

The square root of 818864640 is about 28615.8110141928. The cubic root of 818864640 is about 935.5579766930.

The spelling of 818864640 in words is "eight hundred eighteen million, eight hundred sixty-four thousand, six hundred forty".