66532221 has 24 divisors (see below), whose sum is σ = 110096064. Its totient is φ = 37926720.

The previous prime is 66532201. The next prime is 66532241. The reversal of 66532221 is 12223566.

66532221 is a `hidden beast` number, since 6 + 653 + 2 + 2 + 2 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (66532201) and next prime (66532241).

It is not a de Polignac number, because 66532221 - 2⁵ = 66532189 is a prime.

It is a Curzon number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66532201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31810 + ... + 33836.

It is an arithmetic number, because the mean of its divisors is an integer number (4587336).

Almost surely, 2^66532221 is an apocalyptic number.

It is an amenable number.

66532221 is a deficient number, since it is larger than the sum of its proper divisors (43563843).

66532221 is a wasteful number, since it uses less digits than its factorization.

66532221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2561 (or 2558 counting only the distinct ones).

The product of its digits is 4320, while the sum is 27.

The square root of 66532221 is about 8156.7285721667. The cubic root of 66532221 is about 405.2073743658.

Adding to 66532221 its reverse (12223566), we get a palindrome (78755787).

The spelling of 66532221 in words is "sixty-six million, five hundred thirty-two thousand, two hundred twenty-one".