18221761 has 2 divisors, whose sum is σ = 18221762. Its totient is φ = 18221760.

The previous prime is 18221743. The next prime is 18221783. The reversal of 18221761 is 16712281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15800625 + 2421136 = 3975^2 + 1556^2 .

It is a cyclic number.

It is not a de Polignac number, because 18221761 - 2⁵ = 18221729 is a prime.

It is a super-2 number, since 2×18221761² = 664065147882242, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18221701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9110880 + 9110881.

It is an arithmetic number, because the mean of its divisors is an integer number (9110881).

Almost surely, 2^18221761 is an apocalyptic number.

It is an amenable number.

18221761 is a deficient number, since it is larger than the sum of its proper divisors (1).

18221761 is an equidigital number, since it uses as much as digits as its factorization.

18221761 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1344, while the sum is 28.

The square root of 18221761 is about 4268.6954681729. The cubic root of 18221761 is about 263.1460055674.

The spelling of 18221761 in words is "eighteen million, two hundred twenty-one thousand, seven hundred sixty-one".