18721033 has 2 divisors, whose sum is σ = 18721034. Its totient is φ = 18721032.

The previous prime is 18721009. The next prime is 18721091. The reversal of 18721033 is 33012781.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10036224 + 8684809 = 3168^2 + 2947^2 .

It is an emirp because it is prime and its reverse (33012781) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18721033 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18720989 and 18721007.

It is not a weakly prime, because it can be changed into another prime (18725033) 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, 9360516 + 9360517.

It is an arithmetic number, because the mean of its divisors is an integer number (9360517).

Almost surely, 2^18721033 is an apocalyptic number.

It is an amenable number.

18721033 is a deficient number, since it is larger than the sum of its proper divisors (1).

18721033 is an equidigital number, since it uses as much as digits as its factorization.

18721033 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 18721033 is about 4326.7809050147. The cubic root of 18721033 is about 265.5277627571.

The spelling of 18721033 in words is "eighteen million, seven hundred twenty-one thousand, thirty-three".