18272021 has 2 divisors, whose sum is σ = 18272022. Its totient is φ = 18272020.

The previous prime is 18272017. The next prime is 18272027. The reversal of 18272021 is 12027281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18190225 + 81796 = 4265^2 + 286^2 .

It is a cyclic number.

It is not a de Polignac number, because 18272021 - 2² = 18272017 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18272027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9136010 + 9136011.

It is an arithmetic number, because the mean of its divisors is an integer number (9136011).

Almost surely, 2^18272021 is an apocalyptic number.

It is an amenable number.

18272021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18272021 is an equidigital number, since it uses as much as digits as its factorization.

18272021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 18272021 is about 4274.5784587489. The cubic root of 18272021 is about 263.3877234587.

The spelling of 18272021 in words is "eighteen million, two hundred seventy-two thousand, twenty-one".