18779729 has 2 divisors, whose sum is σ = 18779730. Its totient is φ = 18779728.

The previous prime is 18779723. The next prime is 18779731. The reversal of 18779729 is 92797781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16589329 + 2190400 = 4073^2 + 1480^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18779729 is a prime.

Together with 18779731, 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 (18779723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9389864 + 9389865.

It is an arithmetic number, because the mean of its divisors is an integer number (9389865).

Almost surely, 2^18779729 is an apocalyptic number.

It is an amenable number.

18779729 is a deficient number, since it is larger than the sum of its proper divisors (1).

18779729 is an equidigital number, since it uses as much as digits as its factorization.

18779729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 444528, while the sum is 50.

The square root of 18779729 is about 4333.5584685106. The cubic root of 18779729 is about 265.8049760492.

The spelling of 18779729 in words is "eighteen million, seven hundred seventy-nine thousand, seven hundred twenty-nine".