18729709 has 2 divisors, whose sum is σ = 18729710. Its totient is φ = 18729708.

The previous prime is 18729707. The next prime is 18729721. The reversal of 18729709 is 90792781.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12404484 + 6325225 = 3522^2 + 2515^2 .

It is an emirp because it is prime and its reverse (90792781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18729709 - 2¹ = 18729707 is a prime.

Together with 18729707, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18729703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9364854 + 9364855.

It is an arithmetic number, because the mean of its divisors is an integer number (9364855).

Almost surely, 2^18729709 is an apocalyptic number.

It is an amenable number.

18729709 is a deficient number, since it is larger than the sum of its proper divisors (1).

18729709 is an equidigital number, since it uses as much as digits as its factorization.

18729709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 18729709 is about 4327.7833818249. The cubic root of 18729709 is about 265.5687747939.

The spelling of 18729709 in words is "eighteen million, seven hundred twenty-nine thousand, seven hundred nine".