66814221 has 4 divisors (see below), whose sum is σ = 89085632. Its totient is φ = 44542812.

The previous prime is 66814201. The next prime is 66814229. The reversal of 66814221 is 12241866.

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 not a de Polignac number, because 66814221 - 2¹⁵ = 66781453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66814229) 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, 11135701 + ... + 11135706.

It is an arithmetic number, because the mean of its divisors is an integer number (22271408).

Almost surely, 2^66814221 is an apocalyptic number.

It is an amenable number.

66814221 is a deficient number, since it is larger than the sum of its proper divisors (22271411).

66814221 is a wasteful number, since it uses less digits than its factorization.

66814221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22271410.

The product of its digits is 4608, while the sum is 30.

The square root of 66814221 is about 8173.9966356734. The cubic root of 66814221 is about 405.7790643571.

The spelling of 66814221 in words is "sixty-six million, eight hundred fourteen thousand, two hundred twenty-one".