66146721 has 4 divisors (see below), whose sum is σ = 88195632. Its totient is φ = 44097812.

The previous prime is 66146699. The next prime is 66146741. The reversal of 66146721 is 12764166.

66146721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66146721 - 2⁹ = 66146209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66146741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11024451 + ... + 11024456.

It is an arithmetic number, because the mean of its divisors is an integer number (22048908).

Almost surely, 2^66146721 is an apocalyptic number.

It is an amenable number.

66146721 is a deficient number, since it is larger than the sum of its proper divisors (22048911).

66146721 is a wasteful number, since it uses less digits than its factorization.

66146721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22048910.

The product of its digits is 12096, while the sum is 33.

The square root of 66146721 is about 8133.0634449757. The cubic root of 66146721 is about 404.4232424386.

The spelling of 66146721 in words is "sixty-six million, one hundred forty-six thousand, seven hundred twenty-one".