66571021 has 16 divisors (see below), whose sum is σ = 74882880. Its totient is φ = 58664320.

The previous prime is 66571007. The next prime is 66571033. The reversal of 66571021 is 12017566.

It is not a de Polignac number, because 66571021 - 2⁵ = 66570989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66571081) 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, 51246 + ... + 52528.

It is an arithmetic number, because the mean of its divisors is an integer number (4680180).

Almost surely, 2^66571021 is an apocalyptic number.

It is an amenable number.

66571021 is a deficient number, since it is larger than the sum of its proper divisors (8311859).

66571021 is a wasteful number, since it uses less digits than its factorization.

66571021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1436.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 66571021 is about 8159.1066300178. The cubic root of 66571021 is about 405.2861281418.

Adding to 66571021 its reverse (12017566), we get a palindrome (78588587).

The spelling of 66571021 in words is "sixty-six million, five hundred seventy-one thousand, twenty-one".