1206817721 has 2 divisors, whose sum is σ = 1206817722. Its totient is φ = 1206817720.

The previous prime is 1206817697. The next prime is 1206817753. The reversal of 1206817721 is 1277186021.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1206798121 + 19600 = 34739^2 + 140^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1206817721 is a prime.

It is not a weakly prime, because it can be changed into another prime (1206817021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 603408860 + 603408861.

It is an arithmetic number, because the mean of its divisors is an integer number (603408861).

Almost surely, 2^1206817721 is an apocalyptic number.

It is an amenable number.

1206817721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1206817721 is an equidigital number, since it uses as much as digits as its factorization.

1206817721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9408, while the sum is 35.

The square root of 1206817721 is about 34739.2821025421. The cubic root of 1206817721 is about 1064.6672448198.

The spelling of 1206817721 in words is "one billion, two hundred six million, eight hundred seventeen thousand, seven hundred twenty-one".