823641840 has 240 divisors, whose sum is σ = 3347517888. Its totient is φ = 177168384.

The previous prime is 823641779. The next prime is 823641881. The reversal of 823641840 is 48146328.

823641840 is a `hidden beast` number, since 8 + 2 + 3 + 641 + 8 + 4 + 0 = 666.

823641840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (240).

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 = 823641795 and 823641804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 80874 + ... + 90486.

Almost surely, 2^823641840 is an apocalyptic number.

823641840 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 823641840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1673758944).

823641840 is an abundant number, since it is smaller than the sum of its proper divisors (2523876048).

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

823641840 is a wasteful number, since it uses less digits than its factorization.

823641840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9656 (or 9647 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The square root of 823641840 is about 28699.1609633453. The cubic root of 823641840 is about 937.3737771397.

The spelling of 823641840 in words is "eight hundred twenty-three million, six hundred forty-one thousand, eight hundred forty".