1821018021 has 4 divisors (see below), whose sum is σ = 2428024032. Its totient is φ = 1214012012.

The previous prime is 1821017977. The next prime is 1821018047. The reversal of 1821018021 is 1208101281.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1821018021 - 2²¹ = 1818920869 is a prime.

It is a super-2 number, since 2×1821018021² = 6632213265613512882, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1821017982 and 1821018000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821018071) 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, 303503001 + ... + 303503006.

It is an arithmetic number, because the mean of its divisors is an integer number (607006008).

Almost surely, 2^1821018021 is an apocalyptic number.

It is an amenable number.

1821018021 is a deficient number, since it is larger than the sum of its proper divisors (607006011).

1821018021 is an equidigital number, since it uses as much as digits as its factorization.

1821018021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 607006010.

The product of its (nonzero) digits is 256, while the sum is 24.

The square root of 1821018021 is about 42673.3877375584. The cubic root of 1821018021 is about 1221.1567504502.

The spelling of 1821018021 in words is "one billion, eight hundred twenty-one million, eighteen thousand, twenty-one".