18190821 has 16 divisors (see below), whose sum is σ = 26910720. Its totient is φ = 10836720.

The previous prime is 18190811. The next prime is 18190841. The reversal of 18190821 is 12809181.

It is not a de Polignac number, because 18190821 - 2²¹ = 16093669 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18190811) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2725 + ... + 6618.

It is an arithmetic number, because the mean of its divisors is an integer number (1681920).

Almost surely, 2^18190821 is an apocalyptic number.

18190821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18190821 is a deficient number, since it is larger than the sum of its proper divisors (8719899).

18190821 is a wasteful number, since it uses less digits than its factorization.

18190821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9416.

The product of its (nonzero) digits is 1152, while the sum is 30.

The square root of 18190821 is about 4265.0698704711. The cubic root of 18190821 is about 262.9969831997.

The spelling of 18190821 in words is "eighteen million, one hundred ninety thousand, eight hundred twenty-one".