1821687449 has 2 divisors, whose sum is σ = 1821687450. Its totient is φ = 1821687448.

The previous prime is 1821687437. The next prime is 1821687473. The reversal of 1821687449 is 9447861281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1691841424 + 129846025 = 41132^2 + 11395^2 .

It is a cyclic number.

It is not a de Polignac number, because 1821687449 - 2¹⁶ = 1821621913 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1821687397 and 1821687406.

It is not a weakly prime, because it can be changed into another prime (1821687499) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910843724 + 910843725.

It is an arithmetic number, because the mean of its divisors is an integer number (910843725).

Almost surely, 2^1821687449 is an apocalyptic number.

It is an amenable number.

1821687449 is a deficient number, since it is larger than the sum of its proper divisors (1).

1821687449 is an equidigital number, since it uses as much as digits as its factorization.

1821687449 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 774144, while the sum is 50.

The square root of 1821687449 is about 42681.2306406458. The cubic root of 1821687449 is about 1221.3063693924.

The spelling of 1821687449 in words is "one billion, eight hundred twenty-one million, six hundred eighty-seven thousand, four hundred forty-nine".