66407221 has 8 divisors (see below), whose sum is σ = 67415040. Its totient is φ = 65404512.

The previous prime is 66407213. The next prime is 66407227. The reversal of 66407221 is 12270466.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66407221 - 2³ = 66407213 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66407221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66407227) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30745 + ... + 32833.

It is an arithmetic number, because the mean of its divisors is an integer number (8426880).

Almost surely, 2^66407221 is an apocalyptic number.

It is an amenable number.

66407221 is a deficient number, since it is larger than the sum of its proper divisors (1007819).

66407221 is a wasteful number, since it uses less digits than its factorization.

66407221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2555.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 66407221 is about 8149.0625841259. The cubic root of 66407221 is about 404.9534488994.

Adding to 66407221 its reverse (12270466), we get a palindrome (78677687).

It can be divided in two parts, 6640 and 7221, that added together give a triangular number (13861 = T₁₆₆).

The spelling of 66407221 in words is "sixty-six million, four hundred seven thousand, two hundred twenty-one".