2781981671 has 4 divisors (see below), whose sum is σ = 3179407632. Its totient is φ = 2384555712.

The previous prime is 2781981623. The next prime is 2781981701. The reversal of 2781981671 is 1761891872.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-2781981671 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 (2781981611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 198712970 + ... + 198712983.

It is an arithmetic number, because the mean of its divisors is an integer number (794851908).

Almost surely, 2^2781981671 is an apocalyptic number.

2781981671 is a deficient number, since it is larger than the sum of its proper divisors (397425961).

2781981671 is an equidigital number, since it uses as much as digits as its factorization.

2781981671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397425960.

The product of its digits is 338688, while the sum is 50.

The square root of 2781981671 is about 52744.4942245160. The cubic root of 2781981671 is about 1406.4298915718.

The spelling of 2781981671 in words is "two billion, seven hundred eighty-one million, nine hundred eighty-one thousand, six hundred seventy-one".