18928121 has 2 divisors, whose sum is σ = 18928122. Its totient is φ = 18928120.

The previous prime is 18928109. The next prime is 18928139. The reversal of 18928121 is 12182981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10725625 + 8202496 = 3275^2 + 2864^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18928121 is a prime.

It is not a weakly prime, because it can be changed into another prime (18928141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9464060 + 9464061.

It is an arithmetic number, because the mean of its divisors is an integer number (9464061).

Almost surely, 2^18928121 is an apocalyptic number.

It is an amenable number.

18928121 is a deficient number, since it is larger than the sum of its proper divisors (1).

18928121 is an equidigital number, since it uses as much as digits as its factorization.

18928121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 32.

The square root of 18928121 is about 4350.6460439801. The cubic root of 18928121 is about 266.5032448356.

The spelling of 18928121 in words is "eighteen million, nine hundred twenty-eight thousand, one hundred twenty-one".