1683821561 has 2 divisors, whose sum is σ = 1683821562. Its totient is φ = 1683821560.

The previous prime is 1683821551. The next prime is 1683821569. The reversal of 1683821561 is 1651283861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1643815936 + 40005625 = 40544^2 + 6325^2 .

It is an emirp because it is prime and its reverse (1651283861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1683821561 - 2³⁰ = 610079737 is a prime.

It is not a weakly prime, because it can be changed into another prime (1683821569) 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, 841910780 + 841910781.

It is an arithmetic number, because the mean of its divisors is an integer number (841910781).

Almost surely, 2^1683821561 is an apocalyptic number.

It is an amenable number.

1683821561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1683821561 is an equidigital number, since it uses as much as digits as its factorization.

1683821561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69120, while the sum is 41.

The square root of 1683821561 is about 41034.3948535859. The cubic root of 1683821561 is about 1189.6850992211.

The spelling of 1683821561 in words is "one billion, six hundred eighty-three million, eight hundred twenty-one thousand, five hundred sixty-one".