66694221 has 24 divisors (see below), whose sum is σ = 105764256. Its totient is φ = 40163040.

The previous prime is 66694211. The next prime is 66694223. The reversal of 66694221 is 12249666.

It is not a de Polignac number, because 66694221 - 2⁹ = 66693709 is a prime.

It is a super-2 number, since 2×66694221² = 8896238229593682, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66694223) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14071 + ... + 18203.

It is an arithmetic number, because the mean of its divisors is an integer number (4406844).

Almost surely, 2^66694221 is an apocalyptic number.

It is an amenable number.

66694221 is a deficient number, since it is larger than the sum of its proper divisors (39070035).

66694221 is a wasteful number, since it uses less digits than its factorization.

66694221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4313 (or 4310 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 66694221 is about 8166.6529863831. The cubic root of 66694221 is about 405.5359890173.

The spelling of 66694221 in words is "sixty-six million, six hundred ninety-four thousand, two hundred twenty-one".