66603221 has 4 divisors (see below), whose sum is σ = 68751744. Its totient is φ = 64454700.

The previous prime is 66603211. The next prime is 66603233. The reversal of 66603221 is 12230666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66603221 - 2¹⁰ = 66602197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66603211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1074215 + ... + 1074276.

It is an arithmetic number, because the mean of its divisors is an integer number (17187936).

Almost surely, 2^66603221 is an apocalyptic number.

It is an amenable number.

66603221 is a deficient number, since it is larger than the sum of its proper divisors (2148523).

66603221 is a wasteful number, since it uses less digits than its factorization.

66603221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2148522.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 66603221 is about 8161.0796467134. The cubic root of 66603221 is about 405.3514624248.

Adding to 66603221 its reverse (12230666), we get a palindrome (78833887).

The spelling of 66603221 in words is "sixty-six million, six hundred three thousand, two hundred twenty-one".