18672921 has 12 divisors (see below), whose sum is σ = 27087060. Its totient is φ = 12395520.

The previous prime is 18672859. The next prime is 18672923. The reversal of 18672921 is 12927681.

It can be written as a sum of positive squares in 2 ways, for example, as 9217296 + 9455625 = 3036^2 + 3075^2 .

It is not a de Polignac number, because 18672921 - 2¹³ = 18664729 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (18672923) 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, 2136 + ... + 6473.

It is an arithmetic number, because the mean of its divisors is an integer number (2257255).

Almost surely, 2^18672921 is an apocalyptic number.

It is an amenable number.

18672921 is a deficient number, since it is larger than the sum of its proper divisors (8414139).

18672921 is a wasteful number, since it uses less digits than its factorization.

18672921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8856 (or 8853 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 18672921 is about 4321.2175367597. The cubic root of 18672921 is about 265.3001038255.

The spelling of 18672921 in words is "eighteen million, six hundred seventy-two thousand, nine hundred twenty-one".