17821640449 has 2 divisors, whose sum is σ = 17821640450. Its totient is φ = 17821640448.

The previous prime is 17821640443. The next prime is 17821640471. The reversal of 17821640449 is 94404612871.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16749536400 + 1072104049 = 129420^2 + 32743^2 .

It is a cyclic number.

It is not a de Polignac number, because 17821640449 - 2¹⁵ = 17821607681 is a prime.

It is a super-2 number, since 2×17821640449² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 17821640399 and 17821640408.

It is not a weakly prime, because it can be changed into another prime (17821640443) 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, 8910820224 + 8910820225.

It is an arithmetic number, because the mean of its divisors is an integer number (8910820225).

Almost surely, 2^17821640449 is an apocalyptic number.

It is an amenable number.

17821640449 is a deficient number, since it is larger than the sum of its proper divisors (1).

17821640449 is an equidigital number, since it uses as much as digits as its factorization.

17821640449 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 387072, while the sum is 46.

The spelling of 17821640449 in words is "seventeen billion, eight hundred twenty-one million, six hundred forty thousand, four hundred forty-nine".