820381680 has 120 divisors (see below), whose sum is σ = 2800430880. Its totient is φ = 215170560.

The previous prime is 820381651. The next prime is 820381693. The reversal of 820381680 is 86183028.

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-2 number, since 2×820381680² = 1346052201759244800, which contains 22 as substring.

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

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 34581 + ... + 53259.

It is an arithmetic number, because the mean of its divisors is an integer number (23336924).

Almost surely, 2^820381680 is an apocalyptic number.

820381680 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 820381680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1400215440).

820381680 is an abundant number, since it is smaller than the sum of its proper divisors (1980049200).

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

820381680 is a wasteful number, since it uses less digits than its factorization.

820381680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18759 (or 18750 counting only the distinct ones).

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

The square root of 820381680 is about 28642.3057731042. The cubic root of 820381680 is about 936.1353628469.

The spelling of 820381680 in words is "eight hundred twenty million, three hundred eighty-one thousand, six hundred eighty".