18200021 has 12 divisors (see below), whose sum is σ = 21522060. Its totient is φ = 15341760.

The previous prime is 18199999. The next prime is 18200033. The reversal of 18200021 is 12000281.

It can be written as a sum of positive squares in 2 ways, for example, as 1999396 + 16200625 = 1414^2 + 4025^2 .

It is not a de Polignac number, because 18200021 - 2⁶ = 18199957 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18199969 and 18200005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18200621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 56 + ... + 6033.

It is an arithmetic number, because the mean of its divisors is an integer number (1793505).

Almost surely, 2^18200021 is an apocalyptic number.

It is an amenable number.

18200021 is a deficient number, since it is larger than the sum of its proper divisors (3322039).

18200021 is an equidigital number, since it uses as much as digits as its factorization.

18200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6164 (or 6157 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 18200021 is about 4266.1482627776. The cubic root of 18200021 is about 263.0413125982.

The spelling of 18200021 in words is "eighteen million, two hundred thousand, twenty-one".