66042021 has 16 divisors (see below), whose sum is σ = 91304640. Its totient is φ = 42430080.

The previous prime is 66042007. The next prime is 66042029. The reversal of 66042021 is 12024066.

It is a happy number.

It is not a de Polignac number, because 66042021 - 2¹⁸ = 65779877 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66042029) 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 15 ways as a sum of consecutive naturals, for example, 6975 + ... + 13443.

It is an arithmetic number, because the mean of its divisors is an integer number (5706540).

Almost surely, 2^66042021 is an apocalyptic number.

It is an amenable number.

66042021 is a deficient number, since it is larger than the sum of its proper divisors (25262619).

66042021 is a wasteful number, since it uses less digits than its factorization.

66042021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6596.

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 66042021 is about 8126.6242068894. The cubic root of 66042021 is about 404.2097500015.

Adding to 66042021 its reverse (12024066), we get a palindrome (78066087).

The spelling of 66042021 in words is "sixty-six million, forty-two thousand, twenty-one".