1821801815 has 4 divisors (see below), whose sum is σ = 2186162184. Its totient is φ = 1457441448.

The previous prime is 1821801809. The next prime is 1821801841. The reversal of 1821801815 is 5181081281.

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 1821801815 - 2²² = 1817607511 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 182180177 + ... + 182180186.

It is an arithmetic number, because the mean of its divisors is an integer number (546540546).

Almost surely, 2^1821801815 is an apocalyptic number.

1821801815 is a deficient number, since it is larger than the sum of its proper divisors (364360369).

1821801815 is an equidigital number, since it uses as much as digits as its factorization.

1821801815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364360368.

The product of its (nonzero) digits is 5120, while the sum is 35.

The square root of 1821801815 is about 42682.5703888601. The cubic root of 1821801815 is about 1221.3319268321.

The spelling of 1821801815 in words is "one billion, eight hundred twenty-one million, eight hundred one thousand, eight hundred fifteen".