2861821 has 4 divisors (see below), whose sum is σ = 2986272. Its totient is φ = 2737372.

The previous prime is 2861809. The next prime is 2861849. The reversal of 2861821 is 1281682.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2861821 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2861821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2861801) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62191 + ... + 62236.

It is an arithmetic number, because the mean of its divisors is an integer number (746568).

2^2861821 is an apocalyptic number.

It is an amenable number.

2861821 is a deficient number, since it is larger than the sum of its proper divisors (124451).

2861821 is a wasteful number, since it uses less digits than its factorization.

2861821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124450.

The product of its digits is 1536, while the sum is 28.

The square root of 2861821 is about 1691.6917567926. The cubic root of 2861821 is about 141.9757447165.

The spelling of 2861821 in words is "two million, eight hundred sixty-one thousand, eight hundred twenty-one".