66228021 has 6 divisors (see below), whose sum is σ = 95662710. Its totient is φ = 44152008.

The previous prime is 66227989. The next prime is 66228037. The reversal of 66228021 is 12082266.

It can be written as a sum of positive squares in only one way, i.e., 46991025 + 19236996 = 6855^2 + 4386^2 .

It is not a de Polignac number, because 66228021 - 2⁵ = 66227989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66228061) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3679326 + ... + 3679343.

It is an arithmetic number, because the mean of its divisors is an integer number (15943785).

Almost surely, 2^66228021 is an apocalyptic number.

It is an amenable number.

66228021 is a deficient number, since it is larger than the sum of its proper divisors (29434689).

66228021 is a wasteful number, since it uses less digits than its factorization.

66228021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7358675 (or 7358672 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 66228021 is about 8138.0600268123. The cubic root of 66228021 is about 404.5888648997.

The spelling of 66228021 in words is "sixty-six million, two hundred twenty-eight thousand, twenty-one".