18926821 has 8 divisors (see below), whose sum is σ = 19708920. Its totient is φ = 18153408.

The previous prime is 18926819. The next prime is 18926849. The reversal of 18926821 is 12862981.

It can be written as a sum of positive squares in 4 ways, for example, as 1404225 + 17522596 = 1185^2 + 4186^2 .

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 18926821 - 2¹ = 18926819 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18926851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2475 + ... + 6631.

It is an arithmetic number, because the mean of its divisors is an integer number (2463615).

Almost surely, 2^18926821 is an apocalyptic number.

It is an amenable number.

18926821 is a deficient number, since it is larger than the sum of its proper divisors (782099).

18926821 is a wasteful number, since it uses less digits than its factorization.

18926821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4343.

The product of its digits is 13824, while the sum is 37.

The square root of 18926821 is about 4350.4966383161. The cubic root of 18926821 is about 266.4971434702.

The spelling of 18926821 in words is "eighteen million, nine hundred twenty-six thousand, eight hundred twenty-one".