821767680 has 240 divisors, whose sum is σ = 2953654704. Its totient is φ = 218972160.

The previous prime is 821767637. The next prime is 821767721. The reversal of 821767680 is 86767128.

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

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 621420 + ... + 622740.

Almost surely, 2^821767680 is an apocalyptic number.

821767680 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 821767680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1476827352).

821767680 is an abundant number, since it is smaller than the sum of its proper divisors (2131887024).

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

821767680 is an equidigital number, since it uses as much as digits as its factorization.

821767680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1359 (or 1331 counting only the distinct ones).

The product of its (nonzero) digits is 225792, while the sum is 45.

The square root of 821767680 is about 28666.4905420946. The cubic root of 821767680 is about 936.6622532153.

The spelling of 821767680 in words is "eight hundred twenty-one million, seven hundred sixty-seven thousand, six hundred eighty".