66223121 has 2 divisors, whose sum is σ = 66223122. Its totient is φ = 66223120.

The previous prime is 66223103. The next prime is 66223123. The reversal of 66223121 is 12132266.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 46730896 + 19492225 = 6836^2 + 4415^2 .

It is a cyclic number.

It is not a de Polignac number, because 66223121 - 2⁶ = 66223057 is a prime.

Together with 66223123, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66223123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33111560 + 33111561.

It is an arithmetic number, because the mean of its divisors is an integer number (33111561).

Almost surely, 2^66223121 is an apocalyptic number.

It is an amenable number.

66223121 is a deficient number, since it is larger than the sum of its proper divisors (1).

66223121 is an equidigital number, since it uses as much as digits as its factorization.

66223121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 23.

The square root of 66223121 is about 8137.7589666935. The cubic root of 66223121 is about 404.5788865738.

Adding to 66223121 its reverse (12132266), we get a palindrome (78355387).

The spelling of 66223121 in words is "sixty-six million, two hundred twenty-three thousand, one hundred twenty-one".