1821312305 has 4 divisors (see below), whose sum is σ = 2185574772. Its totient is φ = 1457049840.

The previous prime is 1821312301. The next prime is 1821312347. The reversal of 1821312305 is 5032131281.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1039998001 + 781314304 = 32249^2 + 27952^2 .

It is not a de Polignac number, because 1821312305 - 2² = 1821312301 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1821312301) 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, 182131226 + ... + 182131235.

It is an arithmetic number, because the mean of its divisors is an integer number (546393693).

Almost surely, 2^1821312305 is an apocalyptic number.

It is an amenable number.

1821312305 is a deficient number, since it is larger than the sum of its proper divisors (364262467).

1821312305 is an equidigital number, since it uses as much as digits as its factorization.

1821312305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 364262466.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 1821312305 is about 42676.8356957261. The cubic root of 1821312305 is about 1221.2225282244. Note that the first 3 decimals are identical.

Adding to 1821312305 its reverse (5032131281), we get a palindrome (6853443586).

The spelling of 1821312305 in words is "one billion, eight hundred twenty-one million, three hundred twelve thousand, three hundred five".