18643697 has 2 divisors, whose sum is σ = 18643698. Its totient is φ = 18643696.

The previous prime is 18643657. The next prime is 18643699. The reversal of 18643697 is 79634681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15124321 + 3519376 = 3889^2 + 1876^2 .

It is a cyclic number.

It is not a de Polignac number, because 18643697 - 2⁶ = 18643633 is a prime.

Together with 18643699, 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 (18643699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9321848 + 9321849.

It is an arithmetic number, because the mean of its divisors is an integer number (9321849).

Almost surely, 2^18643697 is an apocalyptic number.

It is an amenable number.

18643697 is a deficient number, since it is larger than the sum of its proper divisors (1).

18643697 is an equidigital number, since it uses as much as digits as its factorization.

18643697 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 44.

The square root of 18643697 is about 4317.8347583019. The cubic root of 18643697 is about 265.1616291786.

The spelling of 18643697 in words is "eighteen million, six hundred forty-three thousand, six hundred ninety-seven".