2861820 has 72 divisors (see below), whose sum is σ = 9356256. Its totient is φ = 703872.

The previous prime is 2861809. The next prime is 2861849. The reversal of 2861820 is 281682.

2861820 is a `hidden beast` number, since 28 + 618 + 20 = 666.

2861820 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is an Ulam number.

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, 1729 + ... + 2951.

It is an arithmetic number, because the mean of its divisors is an integer number (129948).

2^2861820 is an apocalyptic number.

2861820 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 2861820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4678128).

2861820 is an abundant number, since it is smaller than the sum of its proper divisors (6494436).

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

2861820 is a wasteful number, since it uses less digits than its factorization.

2861820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1251 (or 1246 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 2861820 is about 1691.6914612304. The cubic root of 2861820 is about 141.9757281797.

The spelling of 2861820 in words is "two million, eight hundred sixty-one thousand, eight hundred twenty".