18939647 has 2 divisors, whose sum is σ = 18939648. Its totient is φ = 18939646.

The previous prime is 18939643. The next prime is 18939653. The reversal of 18939647 is 74693981.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18939647 - 2² = 18939643 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18939643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9469823 + 9469824.

It is an arithmetic number, because the mean of its divisors is an integer number (9469824).

Almost surely, 2^18939647 is an apocalyptic number.

18939647 is a deficient number, since it is larger than the sum of its proper divisors (1).

18939647 is an equidigital number, since it uses as much as digits as its factorization.

18939647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 47.

The square root of 18939647 is about 4351.9704732454. The cubic root of 18939647 is about 266.5573282656.

The spelling of 18939647 in words is "eighteen million, nine hundred thirty-nine thousand, six hundred forty-seven".