66533021 has 2 divisors, whose sum is σ = 66533022. Its totient is φ = 66533020.

The previous prime is 66533009. The next prime is 66533029. The reversal of 66533021 is 12033566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57592921 + 8940100 = 7589^2 + 2990^2 .

It is a cyclic number.

It is not a de Polignac number, because 66533021 - 2⁶ = 66532957 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66533029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33266510 + 33266511.

It is an arithmetic number, because the mean of its divisors is an integer number (33266511).

Almost surely, 2^66533021 is an apocalyptic number.

It is an amenable number.

66533021 is a deficient number, since it is larger than the sum of its proper divisors (1).

66533021 is an equidigital number, since it uses as much as digits as its factorization.

66533021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3240, while the sum is 26.

The square root of 66533021 is about 8156.7776112874. Note that the first 3 decimals coincide. The cubic root of 66533021 is about 405.2089984641.

Adding to 66533021 its reverse (12033566), we get a palindrome (78566587).

The spelling of 66533021 in words is "sixty-six million, five hundred thirty-three thousand, twenty-one".