66884021 has 2 divisors, whose sum is σ = 66884022. Its totient is φ = 66884020.

The previous prime is 66883991. The next prime is 66884029. The reversal of 66884021 is 12048866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65383396 + 1500625 = 8086^2 + 1225^2 .

It is a cyclic number.

It is not a de Polignac number, because 66884021 - 2¹⁰ = 66882997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66884029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33442010 + 33442011.

It is an arithmetic number, because the mean of its divisors is an integer number (33442011).

Almost surely, 2^66884021 is an apocalyptic number.

It is an amenable number.

66884021 is a deficient number, since it is larger than the sum of its proper divisors (1).

66884021 is an equidigital number, since it uses as much as digits as its factorization.

66884021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18432, while the sum is 35.

The square root of 66884021 is about 8178.2651583328. The cubic root of 66884021 is about 405.9203193223.

The spelling of 66884021 in words is "sixty-six million, eight hundred eighty-four thousand, twenty-one".