18215021 has 8 divisors (see below), whose sum is σ = 19956288. Its totient is φ = 16488000.

The previous prime is 18215017. The next prime is 18215023. The reversal of 18215021 is 12051281.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18215021 - 2² = 18215017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18214984 and 18215002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18215023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 785 + ... + 6086.

It is an arithmetic number, because the mean of its divisors is an integer number (2494536).

Almost surely, 2^18215021 is an apocalyptic number.

18215021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18215021 is a deficient number, since it is larger than the sum of its proper divisors (1741267).

18215021 is a wasteful number, since it uses less digits than its factorization.

18215021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7123.

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 18215021 is about 4267.9059267983. The cubic root of 18215021 is about 263.1135567681.

The spelling of 18215021 in words is "eighteen million, two hundred fifteen thousand, twenty-one".