2778799221 has 12 divisors (see below), whose sum is σ = 4378714080. Its totient is φ = 1684120680.

The previous prime is 2778799183. The next prime is 2778799237. The reversal of 2778799221 is 1229978772.

It is a happy number.

It is not a de Polignac number, because 2778799221 - 2⁹ = 2778798709 is a prime.

It is a super-2 number, since 2×2778799221² = 15443450221260413682, which contains 22 as substring.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2778799291) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14034241 + ... + 14034438.

It is an arithmetic number, because the mean of its divisors is an integer number (364892840).

Almost surely, 2^2778799221 is an apocalyptic number.

It is an amenable number.

2778799221 is a deficient number, since it is larger than the sum of its proper divisors (1599914859).

2778799221 is a wasteful number, since it uses less digits than its factorization.

2778799221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28068696 (or 28068693 counting only the distinct ones).

The product of its digits is 1778112, while the sum is 54.

The square root of 2778799221 is about 52714.3170400604. The cubic root of 2778799221 is about 1405.8933914366.

The spelling of 2778799221 in words is "two billion, seven hundred seventy-eight million, seven hundred ninety-nine thousand, two hundred twenty-one".