66721143 has 4 divisors (see below), whose sum is σ = 88961528. Its totient is φ = 44480760.

The previous prime is 66721139. The next prime is 66721169. The reversal of 66721143 is 34112766.

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

It is not a de Polignac number, because 66721143 - 2² = 66721139 is a prime.

It is a super-3 number, since 3×66721143³ (a number of 24 digits) contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66721143.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66721133) 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 3 ways as a sum of consecutive naturals, for example, 11120188 + ... + 11120193.

It is an arithmetic number, because the mean of its divisors is an integer number (22240382).

Almost surely, 2^66721143 is an apocalyptic number.

66721143 is a deficient number, since it is larger than the sum of its proper divisors (22240385).

66721143 is a wasteful number, since it uses less digits than its factorization.

66721143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22240384.

The product of its digits is 6048, while the sum is 30.

The square root of 66721143 is about 8168.3011085537. The cubic root of 66721143 is about 405.5905483230.

The spelling of 66721143 in words is "sixty-six million, seven hundred twenty-one thousand, one hundred forty-three".