68189921 has 4 divisors (see below), whose sum is σ = 68436372. Its totient is φ = 67943472.

The previous prime is 68189861. The next prime is 68189971. The reversal of 68189921 is 12998186.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 30195025 + 37994896 = 5495^2 + 6164^2 .

It is a cyclic number.

It is not a de Polignac number, because 68189921 - 2⁶ = 68189857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (68189971) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122810 + ... + 123363.

It is an arithmetic number, because the mean of its divisors is an integer number (17109093).

Almost surely, 2^68189921 is an apocalyptic number.

It is an amenable number.

68189921 is a deficient number, since it is larger than the sum of its proper divisors (246451).

68189921 is a wasteful number, since it uses less digits than its factorization.

68189921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246450.

The product of its digits is 62208, while the sum is 44.

The square root of 68189921 is about 8257.7188738779. The cubic root of 68189921 is about 408.5451530564.

The spelling of 68189921 in words is "sixty-eight million, one hundred eighty-nine thousand, nine hundred twenty-one".