2778915891 has 4 divisors (see below), whose sum is σ = 3705221192. Its totient is φ = 1852610592.

The previous prime is 2778915883. The next prime is 2778915901. The reversal of 2778915891 is 1985198772.

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

It is not a de Polignac number, because 2778915891 - 2³ = 2778915883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2778915791) 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, 463152646 + ... + 463152651.

It is an arithmetic number, because the mean of its divisors is an integer number (926305298).

Almost surely, 2^2778915891 is an apocalyptic number.

2778915891 is a deficient number, since it is larger than the sum of its proper divisors (926305301).

2778915891 is an equidigital number, since it uses as much as digits as its factorization.

2778915891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 926305300.

The product of its digits is 2540160, while the sum is 57.

The square root of 2778915891 is about 52715.4236538036. The cubic root of 2778915891 is about 1405.9130669959.

The spelling of 2778915891 in words is "two billion, seven hundred seventy-eight million, nine hundred fifteen thousand, eight hundred ninety-one".