18978529 has 2 divisors, whose sum is σ = 18978530. Its totient is φ = 18978528.

The previous prime is 18978527. The next prime is 18978559. The reversal of 18978529 is 92587981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11833600 + 7144929 = 3440^2 + 2673^2 .

It is a cyclic number.

It is not a de Polignac number, because 18978529 - 2¹ = 18978527 is a prime.

Together with 18978527, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18978527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9489264 + 9489265.

It is an arithmetic number, because the mean of its divisors is an integer number (9489265).

Almost surely, 2^18978529 is an apocalyptic number.

It is an amenable number.

18978529 is a deficient number, since it is larger than the sum of its proper divisors (1).

18978529 is an equidigital number, since it uses as much as digits as its factorization.

18978529 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 362880, while the sum is 49.

The square root of 18978529 is about 4356.4353547367. The cubic root of 18978529 is about 266.7396125093.

The spelling of 18978529 in words is "eighteen million, nine hundred seventy-eight thousand, five hundred twenty-nine".