66927821 has 2 divisors, whose sum is σ = 66927822. Its totient is φ = 66927820.

The previous prime is 66927811. The next prime is 66927829. The reversal of 66927821 is 12872966.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58690921 + 8236900 = 7661^2 + 2870^2 .

It is a cyclic number.

It is not a de Polignac number, because 66927821 - 2¹⁴ = 66911437 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66927829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33463910 + 33463911.

It is an arithmetic number, because the mean of its divisors is an integer number (33463911).

Almost surely, 2^66927821 is an apocalyptic number.

It is an amenable number.

66927821 is a deficient number, since it is larger than the sum of its proper divisors (1).

66927821 is an equidigital number, since it uses as much as digits as its factorization.

66927821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 41.

The square root of 66927821 is about 8180.9425496088. The cubic root of 66927821 is about 406.0089076483.

The spelling of 66927821 in words is "sixty-six million, nine hundred twenty-seven thousand, eight hundred twenty-one".