2991796821 has 24 divisors (see below), whose sum is σ = 4687901400. Its totient is φ = 1827657216.

The previous prime is 2991796729. The next prime is 2991796823. The reversal of 2991796821 is 1286971992.

It can be written as a sum of positive squares in 4 ways, for example, as 1016972100 + 1974824721 = 31890^2 + 44439^2 .

It is not a de Polignac number, because 2991796821 - 2⁷ = 2991796693 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2991796823) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 77296 + ... + 109353.

It is an arithmetic number, because the mean of its divisors is an integer number (195329225).

Almost surely, 2^2991796821 is an apocalyptic number.

It is an amenable number.

2991796821 is a deficient number, since it is larger than the sum of its proper divisors (1696104579).

2991796821 is a wasteful number, since it uses less digits than its factorization.

2991796821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186805 (or 186802 counting only the distinct ones).

The product of its digits is 979776, while the sum is 54.

The square root of 2991796821 is about 54697.3200531799. The cubic root of 2991796821 is about 1440.9338112671.

The spelling of 2991796821 in words is "two billion, nine hundred ninety-one million, seven hundred ninety-six thousand, eight hundred twenty-one".