1683868721 has 2 divisors, whose sum is σ = 1683868722. Its totient is φ = 1683868720.

The previous prime is 1683868651. The next prime is 1683868727. The reversal of 1683868721 is 1278683861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1248562225 + 435306496 = 35335^2 + 20864^2 .

It is a cyclic number.

It is not a de Polignac number, because 1683868721 - 2²² = 1679674417 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1683868721.

It is not a weakly prime, because it can be changed into another prime (1683868727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 841934360 + 841934361.

It is an arithmetic number, because the mean of its divisors is an integer number (841934361).

Almost surely, 2^1683868721 is an apocalyptic number.

It is an amenable number.

1683868721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1683868721 is an equidigital number, since it uses as much as digits as its factorization.

1683868721 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 1683868721 is about 41034.9694894489. The cubic root of 1683868721 is about 1189.6962059058.

The spelling of 1683868721 in words is "one billion, six hundred eighty-three million, eight hundred sixty-eight thousand, seven hundred twenty-one".