66552821 has 2 divisors, whose sum is σ = 66552822. Its totient is φ = 66552820.

The previous prime is 66552809. The next prime is 66552887. The reversal of 66552821 is 12825566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66422500 + 130321 = 8150^2 + 361^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66552821 is a prime.

It is equal to p_3926951 and since 66552821 and 3926951 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66552121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33276410 + 33276411.

It is an arithmetic number, because the mean of its divisors is an integer number (33276411).

Almost surely, 2^66552821 is an apocalyptic number.

It is an amenable number.

66552821 is a deficient number, since it is larger than the sum of its proper divisors (1).

66552821 is an equidigital number, since it uses as much as digits as its factorization.

66552821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28800, while the sum is 35.

The square root of 66552821 is about 8157.9912355923. The cubic root of 66552821 is about 405.2491907491.

The spelling of 66552821 in words is "sixty-six million, five hundred fifty-two thousand, eight hundred twenty-one".