18997409 has 2 divisors, whose sum is σ = 18997410. Its totient is φ = 18997408.

The previous prime is 18997387. The next prime is 18997411. The reversal of 18997409 is 90479981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18037009 + 960400 = 4247^2 + 980^2 .

It is a cyclic number.

It is not a de Polignac number, because 18997409 - 2¹² = 18993313 is a prime.

Together with 18997411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18997439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9498704 + 9498705.

It is an arithmetic number, because the mean of its divisors is an integer number (9498705).

Almost surely, 2^18997409 is an apocalyptic number.

It is an amenable number.

18997409 is a deficient number, since it is larger than the sum of its proper divisors (1).

18997409 is an equidigital number, since it uses as much as digits as its factorization.

18997409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 163296, while the sum is 47.

The square root of 18997409 is about 4358.6017253243. The cubic root of 18997409 is about 266.8280347968.

The spelling of 18997409 in words is "eighteen million, nine hundred ninety-seven thousand, four hundred nine".