18020821 has 8 divisors (see below), whose sum is σ = 22179584. Its totient is φ = 14258160.

The previous prime is 18020819. The next prime is 18020831. The reversal of 18020821 is 12802081.

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

It is not a de Polignac number, because 18020821 - 2¹ = 18020819 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18020792 and 18020801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18020831) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 98925 + ... + 99106.

It is an arithmetic number, because the mean of its divisors is an integer number (2772448).

Almost surely, 2^18020821 is an apocalyptic number.

It is an amenable number.

18020821 is a deficient number, since it is larger than the sum of its proper divisors (4158763).

18020821 is a wasteful number, since it uses less digits than its factorization.

18020821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198051.

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 18020821 is about 4245.0937563262. The cubic root of 18020821 is about 262.1751494777.

The spelling of 18020821 in words is "eighteen million, twenty thousand, eight hundred twenty-one".