18408921 has 8 divisors (see below), whose sum is σ = 24881760. Its totient is φ = 12104352.

The previous prime is 18408917. The next prime is 18408937. The reversal of 18408921 is 12980481.

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

It is not a de Polignac number, because 18408921 - 2² = 18408917 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18408941) 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 7 ways as a sum of consecutive naturals, for example, 41811 + ... + 42248.

It is an arithmetic number, because the mean of its divisors is an integer number (3110220).

Almost surely, 2^18408921 is an apocalyptic number.

It is an amenable number.

18408921 is a deficient number, since it is larger than the sum of its proper divisors (6472839).

18408921 is an equidigital number, since it uses as much as digits as its factorization.

18408921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84135.

The product of its (nonzero) digits is 4608, while the sum is 33.

The square root of 18408921 is about 4290.5618513197. The cubic root of 18408921 is about 264.0438833158.

The spelling of 18408921 in words is "eighteen million, four hundred eight thousand, nine hundred twenty-one".