68443721 has 4 divisors (see below), whose sum is σ = 68467092. Its totient is φ = 68420352.

The previous prime is 68443663. The next prime is 68443733. The reversal of 68443721 is 12734486.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12734486 = 2 ⋅6367243.

It can be written as a sum of positive squares in 2 ways, for example, as 17106496 + 51337225 = 4136^2 + 7165^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-68443721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (68443021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6536 + ... + 13401.

It is an arithmetic number, because the mean of its divisors is an integer number (17116773).

Almost surely, 2^68443721 is an apocalyptic number.

It is an amenable number.

68443721 is a deficient number, since it is larger than the sum of its proper divisors (23371).

68443721 is a wasteful number, since it uses less digits than its factorization.

68443721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23370.

The product of its digits is 32256, while the sum is 35.

The square root of 68443721 is about 8273.0720412674. The cubic root of 68443721 is about 409.0513881028.

The spelling of 68443721 in words is "sixty-eight million, four hundred forty-three thousand, seven hundred twenty-one".