2781253861 has 4 divisors (see below), whose sum is σ = 2782383712. Its totient is φ = 2780124012.

The previous prime is 2781253847. The next prime is 2781253897. The reversal of 2781253861 is 1683521872.

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 2781253861 - 2⁷ = 2781253733 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 (2781253831) 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, 561225 + ... + 566158.

It is an arithmetic number, because the mean of its divisors is an integer number (695595928).

Almost surely, 2^2781253861 is an apocalyptic number.

It is an amenable number.

2781253861 is a deficient number, since it is larger than the sum of its proper divisors (1129851).

2781253861 is a wasteful number, since it uses less digits than its factorization.

2781253861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1129850.

The product of its digits is 161280, while the sum is 43.

The square root of 2781253861 is about 52737.5943801004. The cubic root of 2781253861 is about 1406.3072328417.

The spelling of 2781253861 in words is "two billion, seven hundred eighty-one million, two hundred fifty-three thousand, eight hundred sixty-one".