66724421 has 2 divisors, whose sum is σ = 66724422. Its totient is φ = 66724420.

The previous prime is 66724397. The next prime is 66724453. The reversal of 66724421 is 12442766.

66724421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an a-pointer prime, because the next prime (66724453) can be obtained adding 66724421 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66601921 + 122500 = 8161^2 + 350^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66724421 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 (66724321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33362210 + 33362211.

It is an arithmetic number, because the mean of its divisors is an integer number (33362211).

Almost surely, 2^66724421 is an apocalyptic number.

It is an amenable number.

66724421 is a deficient number, since it is larger than the sum of its proper divisors (1).

66724421 is an equidigital number, since it uses as much as digits as its factorization.

66724421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16128, while the sum is 32.

The square root of 66724421 is about 8168.5017598088. The cubic root of 66724421 is about 405.5971904157.

The spelling of 66724421 in words is "sixty-six million, seven hundred twenty-four thousand, four hundred twenty-one".