2778991447 has 4 divisors (see below), whose sum is σ = 2810216160. Its totient is φ = 2747766736.

The previous prime is 2778991427. The next prime is 2778991469. The reversal of 2778991447 is 7441998772.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2778991447 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2778991391 and 2778991400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2778991427) 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, 15612223 + ... + 15612400.

It is an arithmetic number, because the mean of its divisors is an integer number (702554040).

Almost surely, 2^2778991447 is an apocalyptic number.

2778991447 is a deficient number, since it is larger than the sum of its proper divisors (31224713).

2778991447 is an equidigital number, since it uses as much as digits as its factorization.

2778991447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31224712.

The product of its digits is 7112448, while the sum is 58.

The square root of 2778991447 is about 52716.1402892890. The cubic root of 2778991447 is about 1405.9258086800.

The spelling of 2778991447 in words is "two billion, seven hundred seventy-eight million, nine hundred ninety-one thousand, four hundred forty-seven".