66771021 has 16 divisors (see below), whose sum is σ = 92367360. Its totient is φ = 42853440.

The previous prime is 66771011. The next prime is 66771031. The reversal of 66771021 is 12017766.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (66771011) and next prime (66771031).

It is not a de Polignac number, because 66771021 - 2¹⁵ = 66738253 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66771021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66771011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35716 + ... + 37538.

It is an arithmetic number, because the mean of its divisors is an integer number (5772960).

Almost surely, 2^66771021 is an apocalyptic number.

It is an amenable number.

66771021 is a deficient number, since it is larger than the sum of its proper divisors (25596339).

66771021 is a wasteful number, since it uses less digits than its factorization.

66771021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2276.

The product of its (nonzero) digits is 3528, while the sum is 30.

The square root of 66771021 is about 8171.3536822243. The cubic root of 66771021 is about 405.6915907887.

Adding to 66771021 its reverse (12017766), we get a palindrome (78788787).

The spelling of 66771021 in words is "sixty-six million, seven hundred seventy-one thousand, twenty-one".