820861280 has 96 divisors (see below), whose sum is σ = 2002571424. Its totient is φ = 317730816.

The previous prime is 820861229. The next prime is 820861289. The reversal of 820861280 is 82168028.

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 820861280.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820861289) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1852739 + ... + 1853181.

It is an arithmetic number, because the mean of its divisors is an integer number (20860119).

Almost surely, 2^820861280 is an apocalyptic number.

820861280 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 820861280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1001285712).

820861280 is an abundant number, since it is smaller than the sum of its proper divisors (1181710144).

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

820861280 is a wasteful number, since it uses less digits than its factorization.

820861280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 808 (or 800 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 35.

The square root of 820861280 is about 28650.6767808371. The cubic root of 820861280 is about 936.3177507399.

The spelling of 820861280 in words is "eight hundred twenty million, eight hundred sixty-one thousand, two hundred eighty".