2646821891 has 4 divisors (see below), whose sum is σ = 3024939312. Its totient is φ = 2268704472.

The previous prime is 2646821867. The next prime is 2646821893. The reversal of 2646821891 is 1981286462.

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

It is a cyclic number.

It is not a de Polignac number, because 2646821891 - 2¹⁰ = 2646820867 is a prime.

It is a super-2 number, since 2×2646821891² = 14011332245353631762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2646821893) 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, 189058700 + ... + 189058713.

It is an arithmetic number, because the mean of its divisors is an integer number (756234828).

Almost surely, 2^2646821891 is an apocalyptic number.

2646821891 is a deficient number, since it is larger than the sum of its proper divisors (378117421).

2646821891 is an equidigital number, since it uses as much as digits as its factorization.

2646821891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 378117420.

The product of its digits is 331776, while the sum is 47.

The square root of 2646821891 is about 51447.2729209236. The cubic root of 2646821891 is about 1383.2740805059.

The spelling of 2646821891 in words is "two billion, six hundred forty-six million, eight hundred twenty-one thousand, eight hundred ninety-one".