1683366721 has 2 divisors, whose sum is σ = 1683366722. Its totient is φ = 1683366720.

The previous prime is 1683366719. The next prime is 1683366829. The reversal of 1683366721 is 1276633861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1410753600 + 272613121 = 37560^2 + 16511^2 .

It is a cyclic number.

It is not a de Polignac number, because 1683366721 - 2¹ = 1683366719 is a prime.

Together with 1683366719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1683366221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 841683360 + 841683361.

It is an arithmetic number, because the mean of its divisors is an integer number (841683361).

Almost surely, 2^1683366721 is an apocalyptic number.

It is an amenable number.

1683366721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1683366721 is an equidigital number, since it uses as much as digits as its factorization.

1683366721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 43.

The square root of 1683366721 is about 41028.8522993271. The cubic root of 1683366721 is about 1189.5779688867.

The spelling of 1683366721 in words is "one billion, six hundred eighty-three million, three hundred sixty-six thousand, seven hundred twenty-one".