18690921 has 12 divisors (see below), whose sum is σ = 27043380. Its totient is φ = 12439680.

The previous prime is 18690911. The next prime is 18690929. The reversal of 18690921 is 12909681.

It can be written as a sum of positive squares in 2 ways, for example, as 8037225 + 10653696 = 2835^2 + 3264^2 .

It is not a de Polignac number, because 18690921 - 2⁶ = 18690857 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18690929) 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 11 ways as a sum of consecutive naturals, for example, 5485 + ... + 8213.

It is an arithmetic number, because the mean of its divisors is an integer number (2253615).

Almost surely, 2^18690921 is an apocalyptic number.

It is an amenable number.

18690921 is a deficient number, since it is larger than the sum of its proper divisors (8352459).

18690921 is a wasteful number, since it uses less digits than its factorization.

18690921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3496 (or 3493 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 18690921 is about 4323.2997814170. The cubic root of 18690921 is about 265.3853229199.

The spelling of 18690921 in words is "eighteen million, six hundred ninety thousand, nine hundred twenty-one".