18705409 has 2 divisors, whose sum is σ = 18705410. Its totient is φ = 18705408.

The previous prime is 18705341. The next prime is 18705439. The reversal of 18705409 is 90450781.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16224784 + 2480625 = 4028^2 + 1575^2 .

It is an emirp because it is prime and its reverse (90450781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18705409 - 2²¹ = 16608257 is a prime.

It is not a weakly prime, because it can be changed into another prime (18705439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9352704 + 9352705.

It is an arithmetic number, because the mean of its divisors is an integer number (9352705).

Almost surely, 2^18705409 is an apocalyptic number.

It is an amenable number.

18705409 is a deficient number, since it is larger than the sum of its proper divisors (1).

18705409 is an equidigital number, since it uses as much as digits as its factorization.

18705409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 18705409 is about 4324.9750288296. The cubic root of 18705409 is about 265.4538750893.

The spelling of 18705409 in words is "eighteen million, seven hundred five thousand, four hundred nine".