2861809920 has 288 divisors, whose sum is σ = 10755037440. Its totient is φ = 718110720.

The previous prime is 2861809913. The next prime is 2861809921. The reversal of 2861809920 is 299081682.

2861809920 is a `hidden beast` number, since 2 + 8 + 618 + 0 + 9 + 9 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2861809921) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 585085 + ... + 589955.

It is an arithmetic number, because the mean of its divisors is an integer number (37343880).

Almost surely, 2^2861809920 is an apocalyptic number.

2861809920 is a gapful number since it is divisible by the number (20) 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 2861809920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (5377518720).

2861809920 is an abundant number, since it is smaller than the sum of its proper divisors (7893227520).

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

2861809920 is a wasteful number, since it uses less digits than its factorization.

2861809920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4918 (or 4898 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 2861809920 is about 53495.8869446988. The cubic root of 2861809920 is about 1419.7556148896.

The spelling of 2861809920 in words is "two billion, eight hundred sixty-one million, eight hundred nine thousand, nine hundred twenty".