2780861 has 4 divisors (see below), whose sum is σ = 2901792. Its totient is φ = 2659932.

The previous prime is 2780837. The next prime is 2780873. The reversal of 2780861 is 1680872.

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 not a de Polignac number, because 2780861 - 2⁶ = 2780797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2780801) 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, 60431 + ... + 60476.

It is an arithmetic number, because the mean of its divisors is an integer number (725448).

2^2780861 is an apocalyptic number.

It is an amenable number.

2780861 is a deficient number, since it is larger than the sum of its proper divisors (120931).

2780861 is a wasteful number, since it uses less digits than its factorization.

2780861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120930.

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 2780861 is about 1667.5913768067. The cubic root of 2780861 is about 140.6241014593.

The spelling of 2780861 in words is "two million, seven hundred eighty thousand, eight hundred sixty-one".