68091821 has 6 divisors (see below), whose sum is σ = 79208910. Its totient is φ = 58364376.

The previous prime is 68091811. The next prime is 68091823. The reversal of 68091821 is 12819086.

It can be written as a sum of positive squares in only one way, i.e., 38812900 + 29278921 = 6230^2 + 5411^2 .

It is not a de Polignac number, because 68091821 - 2⁶ = 68091757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68091823) 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 in 5 ways as a sum of consecutive naturals, for example, 694766 + ... + 694863.

It is an arithmetic number, because the mean of its divisors is an integer number (13201485).

Almost surely, 2^68091821 is an apocalyptic number.

It is an amenable number.

68091821 is a deficient number, since it is larger than the sum of its proper divisors (11117089).

68091821 is a wasteful number, since it uses less digits than its factorization.

68091821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1389643 (or 1389636 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 68091821 is about 8251.7768389602. The cubic root of 68091821 is about 408.3491440590.

The spelling of 68091821 in words is "sixty-eight million, ninety-one thousand, eight hundred twenty-one".