18909471709 has 2 divisors, whose sum is σ = 18909471710. Its totient is φ = 18909471708.

The previous prime is 18909471661. The next prime is 18909471733. The reversal of 18909471709 is 90717490981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18040519225 + 868952484 = 134315^2 + 29478^2 .

It is a cyclic number.

It is not a de Polignac number, because 18909471709 - 2¹¹ = 18909469661 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18909471709.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18909471799) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9454735854 + 9454735855.

It is an arithmetic number, because the mean of its divisors is an integer number (9454735855).

Almost surely, 2^18909471709 is an apocalyptic number.

It is an amenable number.

18909471709 is a deficient number, since it is larger than the sum of its proper divisors (1).

18909471709 is an equidigital number, since it uses as much as digits as its factorization.

18909471709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1143072, while the sum is 55.

The spelling of 18909471709 in words is "eighteen billion, nine hundred nine million, four hundred seventy-one thousand, seven hundred nine".