18107921 has 8 divisors (see below), whose sum is σ = 19574184. Its totient is φ = 16652160.

The previous prime is 18107917. The next prime is 18107933. The reversal of 18107921 is 12970181.

It can be written as a sum of positive squares in 4 ways, for example, as 3857296 + 14250625 = 1964^2 + 3775^2 .

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 18107921 - 2² = 18107917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18107981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1175 + ... + 6131.

It is an arithmetic number, because the mean of its divisors is an integer number (2446773).

Almost surely, 2^18107921 is an apocalyptic number.

It is an amenable number.

18107921 is a deficient number, since it is larger than the sum of its proper divisors (1466263).

18107921 is a wasteful number, since it uses less digits than its factorization.

18107921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5251.

The product of its (nonzero) digits is 1008, while the sum is 29.

The square root of 18107921 is about 4255.3402919156. The cubic root of 18107921 is about 262.5968610043.

The spelling of 18107921 in words is "eighteen million, one hundred seven thousand, nine hundred twenty-one".